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NAME
nail - send and receive Internet mail
SYNOPSIS
nail [-BDdFintv~] [-s subject] [-a attachment ] [-c cc-addr] [-b bcc-
addr] [-r from-addr] [-h hops] [-A account] to-addr . . .
nail [-BDdeHiInNRv~] [-T name] [-A account] -f [name]
nail [-BDdeinNRv~] [-A account] [-u user]
DESCRIPTION
Nail is an intelligent mail processing system, which has a command
syntax reminiscent of ed(1) with lines replaced by messages. It is
based on Berkeley Mail 8.1, is intended to provide the functionality
of the POSIX mailx command, and offers extensions for MIME, IMAP,
POP3, SMTP, and S/MIME. Nail provides enhanced features for
interactive use, such as caching and disconnected operation for IMAP,
message threading, scoring, and filtering. It is also usable as a
mail batch language, both for sending and receiving mail.
The following options are accepted:
-A name
Executes an account command (see below) for name after the
startup files have been read.
-a file
Attach the given file to the message.
-B Make standard input and standard output line-buffered.
-b address
Send blind carbon copies to list. List should be a comma-
separated list of names.
-c address
Send carbon copies to list of users.
-D Start in disconnected mode; see the description for the
disconnected variable option.
-d Enables debugging messages and disables the actual delivery of
messages. Unlike -v, this option is intended for nail
development only.
-e Just check if mail is present in the system mailbox. If yes,
return an exit status of zero, else, a non-zero value.
-f [file]
Read in the contents of the user's mbox (or the specified file)
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for processing; when nail is quit, it writes undeleted messages
back to this file. The string file is handled as described for
the folder command below.
-F Save the message to send in a file named after the local part of
the first recipient's address.
-H Print header summaries for all messages and exit.
-h hops
Invoke sendmail with the specified hop count. This option has no
effect when SMTP is used for sending mail.
-i Ignore tty interrupt signals. This is particularly useful when
using nail on noisy phone lines.
-I Shows the `Newsgroup:' or `Article-Id:' fields in the header
summary. Only applicable in combination with -f.
-n Inhibits reading /etc/nail.rc upon startup. This option should
be activated for nail scripts that are invoked on more than one
machine, because the contents of that file may differ between
them.
-N Inhibits the initial display of message headers when reading mail
or editing a mail folder.
-q file
Start the message with the contents of the specified file. May
be given in send mode only.
-r address
Sets the From address. Overrides any from variable specified in
environment or startup files. Tilde escapes are disabled. The
-r address options are passed to the mail transfer agent unless
SMTP is used. This option exists for compatibility only; it is
recommended to set the from variable directly instead.
-R Opens any folders read-only.
-s subject
Specify subject on command line (only the first argument after
the -s flag is used as a subject; be careful to quote subjects
containing spaces).
-T name
Writes the `Message-Id:' and `Article-Id:' header fields of each
message read in the file name. Implies -I. Compressed files are
handled as described for the folder command below.
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-t The message to be sent is expected to contain a message header
with `To:', `Cc:', or `Bcc:' fields giving its recipients.
Recipients specified on the command line are ignored.
-u user
Reads the mailbox of the given user name.
-v Verbose mode. The details of delivery are displayed on the
user's terminal.
-V Print nail's version and exit.
-~ Enable tilde escapes even if not in interactive mode.
Sending mail
To send a message to one or more people, nail can be invoked with
arguments which are the names of people to whom the mail will be sent.
The user is then expected to type in his message, followed by an
`control-D' at the beginning of a line. The section below Replying to
or originating mail, describes some features of nail available to help
when composing letters.
Reading mail
In normal usage nail is given no arguments and checks the user's mail
out of the post office, then prints out a one line header of each
message found. The current message is initially the first message
(numbered 1) and can be printed using the print command which can be
abbreviated `p'). The user can move among the messages much as he
moves between lines in ed(1), with the commands `+' and `-' moving
backwards and forwards, and simple numbers.
Disposing of mail
After examining a message the user can delete `d') the message or
reply `r') to it. Deletion causes the nail program to forget about
the message. This is not irreversible; the message can be undeleted
`u') by giving its number, or the nail session can be aborted by
giving the exit `x') command. Deleted messages will, however, usually
disappear never to be seen again.
Specifying messages
Commands such as print and delete can be given a list of message
numbers as arguments to apply to a number of messages at once. Thus
`delete 1 2' deletes messages 1 and 2, while `delete 1-5' deletes
messages 1 through 5. In sorted or threaded mode (see the sort and
thread commands), `delete 1-5' deletes the messages that are located
between (and including) messages 1 through 5 in the sorted/threaded
order, as shown in the header summary. The following special message
names exist:
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:n All new messages.
:o All old messages (any not in state read or new).
:u All unread messages.
:d All deleted messages (for the undelete command).
:r All read messages.
:f All `flagged' messages.
:a All answered messages (cf. the markanswered variable).
:t All messages marked as draft.
:k All `killed' messages.
:j All messages classified as junk.
. The current message.
; The message that was previously the current message.
, The parent message of the current message, that is the message
with the Message-ID given in the `In-Reply-To:' field or the last
entry of the `References:' field of the current message.
- The next previous undeleted message, or the next previous deleted
message for the undelete command. In sorted/threaded mode, the
next previous such message in the sorted/threaded order.
+ The next undeleted message, or the next deleted message for the
undelete command. In sorted/threaded mode, the next such message
in the sorted/threaded order.
^ The first undeleted message, or the first deleted message for the
undelete command. In sorted/threaded mode, the first such
message in the sorted/threaded order.
$ The last message. In sorted/threaded mode, the last message in
the sorted/threaded order.
&x In threaded mode, selects the message addressed with x, where x
is any other message specification, and all messages from the
thread that begins at it. Otherwise, it is identical to x. If x
is omitted, the thread beginning with the current message is
selected.
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* All messages.
` All messages that were included in the message list for the
previous command.
/string
All messages that contain string in the subject field (case
ignored). See also the searchheaders variable. If string is
empty, the string from the previous specification of that type is
used again.
address
All messages from address.
(criterion)
All messages that satisfy the given IMAP-style SEARCH criterion.
This addressing mode is available with all types of folders; for
folders not located on IMAP servers, or for servers unable to
execute the SEARCH command, nail will perform the search locally.
Strings must be enclosed by double quotes `"' in their entirety
if they contain white space or parentheses; within the quotes,
only backslash `\' is recognized as an escape character. All
string searches are case-insensitive. When the description
indicates that the `envelope' representation of an address field
is used, this means that the search string is checked against
both a list constructed as
("real name" "source-route" "local-part" "domain-part")
for each address, and the addresses without real names from the
respective header field. Criteria can be nested using
parentheses.
(criterion1 criterion2 ... criterionN)
All messages that satisfy all of the given criteria.
(or criterion1 criterion2)
All messages that satisfy either criterion1 or criterion2, or
both. To connect more than two criteria using `or', (or)
specifications have to be nested using additional parentheses, as
with `(or a (or b c))'; `(or a b c)' means ((a or b) and c). For
a simple `or' operation of independent criteria on the lowest
nesting level, it is possible to achieve similar effects by using
three separate criteria, as with `(a) (b) (c)'.
(not criterion)
All messages that do not satisfy criterion.
(bcc string)
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All messages that contain string in the `envelope' representation
of the Bcc: field.
(cc string)
All messages that contain string in the `envelope' representation
of the Cc: field.
(from string)
All messages that contain string in the `envelope' representation
of the From: field.
(subject string)
All messages that contain string in the Subject: field.
(to string)
All messages that contain string in the `envelope' representation
of the To: field.
(header name string)
All messages that contain string in the specified Name: field.
(body string)
All messages that contain string in their body.
(text string)
All messages that contain string in their header or body.
(larger size)
All messages that are larger than size (in bytes).
(smaller size)
All messages that are smaller than size (in bytes).
(before date)
All messages that were received before date; date must be in the
form d[d]-mon-yyyy, where d[d] is the day of the month as one or
two digits, mon is the name of the month-one of `Jan', `Feb',
`Mar', `Apr', `May', `Jun', `Jul', `Aug', `Sep', `Oct', `Nov', or
`Dec', and yyyy is the year as four digits; e.g. "30-Aug-2004".
(on date)
All messages that were received on the specified date.
(since date)
All messages that were received since the specified date.
(sentbefore date)
All messages that were sent on the specified date.
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(senton date)
All messages that were sent on the specified date.
(sentsince date)
All messages that were sent since the specified date.
() The same criterion as for the previous search. This
specification cannot be used as part of another criterion. If
the previous command line contained more than one independent
criterion, the last of those criteria is used.
A practical method to read a set of messages is to issue a from
command with the search criteria first to check for appropriate
messages, and to read each single message then by typing ``'
repeatedly.
Replying to or originating mail
The reply command can be used to set up a response to a message,
sending it back to the person who it was from. Text the user types in
then, up to an end-of-file, defines the contents of the message.
While the user is composing a message, nail treats lines beginning
with the character `~' specially. For instance, typing `~m' (alone on
a line) will place a copy of the current message into the response
right shifting it by a tabstop (see indentprefix variable, below).
Other escapes will set up subject fields, add and delete recipients to
the message, attach files to it and allow the user to escape to an
editor to revise the message or to a shell to run some commands.
(These options are given in the summary below.)
Ending a mail processing session
The user can end a nail session with the quit (`q') command. Messages
which have been examined go to the user's mbox file unless they have
been deleted in which case they are discarded. Unexamined messages go
back to the post office. (See the -f option above).
Personal and systemwide distribution lists
It is also possible to create a personal distribution lists so that,
for instance, the user can send mail to `cohorts' and have it go to a
group of people. Such lists can be defined by placing a line like
alias cohorts bill ozalp jkf mark kridle@ucbcory
in the file .mailrc in the user's home directory. The current list of
such aliases can be displayed with the alias command in nail. System
wide distribution lists can be created by editing /etc/aliases, see
aliases(5) and sendmail(8); these are kept in a different syntax. In
mail the user sends, personal aliases will be expanded in mail sent to
others so that they will be able to reply to the recipients. System
wide aliases are not expanded when the mail is sent, but any reply
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returned to the machine will have the system wide alias expanded as
all mail goes through sendmail.
Recipient address specifications
When an address is used to name a recipient (in any of To, Cc, or
Bcc), names of local mail folders and pipes to external commands can
also be specified; the message text is then written to them. The
rules are: Any name which starts with a `|' character specifies a
pipe, the command string following the `|' is executed and the message
is sent to its standard input; any other name which contains a `@'
character is treated as a mail address; any other name which starts
with a `+' character specifies a folder name; any other name which
contains a `/' character but no `!' or `%' character before also
specifies a folder name; what remains is treated as a mail address.
Compressed folders are handled as described for the folder command
below.
Network mail (Internet / ARPA, UUCP, Berknet)
See mailaddr(7) for a description of network addresses. Nail has a
number of options which can be set in the .mailrc file to alter its
behavior; thus `set askcc' enables the askcc feature. (These options
are summarized below).
MIME types
For any outgoing attachment, nail tries to determine the content type.
It does this by reading MIME type files whose lines have the following
syntax:
type/subtype extension [extension . . .]
where type/subtype are strings describing the file contents, and
extension is the part of a filename starting after the last dot. Any
line not immediately beginning with an ASCII alphabetical character is
ignored by nail. If there is a match with the extension of the file
to attach, the given type/subtype pair is used. Otherwise, or if the
filename has no extension, the content types text/plain or
application/octet-stream are used, the first for text or international
text files, the second for any file that contains formatting
characters other than newlines and horizontal tabulators.
Character sets
Nail normally detects the character set of the terminal using the
LC_CTYPE locale setting. If the locale cannot be used appropriately,
the ttycharset variable should be set to provide an explicit value.
When reading messages, their text is converted to the terminal
character set if possible. Unprintable characters and illegal byte
sequences are detected and replaced by Unicode substitute characters
or question marks unless the print-all-chars is set at initialization
time.
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The character set for outgoing messages is not necessarily the same as
the one used on the terminal. If an outgoing text message contains
characters not representable in US-ASCII, the character set being used
must be declared within its header. Permissible values can be
declared using the sendcharsets variable, separated by commas; nail
tries each of the values in order and uses the first appropriate one.
If the message contains characters that cannot be represented in any
of the given character sets, the message will not be sent, and its
text will be saved to the `dead.letter' file. Messages that contains
NUL bytes are not converted.
Outgoing attachments are also not converted even if they are plain
text. If the sendcharsets variable contains more than one character
set name, the ~@ tilde escape will ask for the character sets for
individual attachments if it is invoked without arguments.
Best results are usually achieved when nail is run in a UTF-8 locale
on a UTF-8 capable terminal. In this setup, characters from various
countries can be displayed, while it is still possible to use more
simple character sets for sending to retain maximum compatibility with
older mail clients.
Commands
Each command is typed on a line by itself, and may take arguments
following the command word. The command need not be typed in its
entirety the first command which matches the typed prefix is used.
For commands which take message lists as arguments, if no message list
is given, then the next message forward which satisfies the command's
requirements is used. If there are no messages forward of the current
message, the search proceeds backwards, and if there are no good
messages at all, nail types `applicable messages' and aborts the
command. If the command begins with a # sign, the line is ignored.
The arguments to commands can be quoted, using the following methods:
+ An argument can be enclosed between paired double-quotes "" or
single-quotes ''; any white space, shell word expansion, or
backslash characters within the quotes are treated literally as
part of the argument. A double-quote will be treated literally
within single-quotes and vice versa. These special properties of
the quote marks occur only when they are paired at the beginning
and end of the argument.
+ A backslash outside of the enclosing quotes is discarded and the
following character is treated literally as part of the argument.
+ An unquoted backslash at the end of a command line is discarded
and the next line continues the command.
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Filenames, where expected, are subjected to the following
transformations, in sequence:
+ If the filename begins with an unquoted plus sign, and the folder
variable is defined, the plus sign will be replaced by the value
of the folder variable followed by a slash. If the folder
variable is unset or is set to null, the filename will be
unchanged.
+ Shell word expansions are applied to the filename. If more than
a single pathname results from this expansion and the command is
expecting one file, an error results.
The following commands are provided:
- Print out the preceding message. If given a numeric argument n,
goes to the n'th previous message and prints it.
? Prints a brief summary of commands.
! Executes the shell (see sh(1) and csh(1)) command which follows.
| A synonym for the pipe command.
account
(ac) Creates, selects or lists an email account. An account is
formed by a group of commands, primarily of those to set
variables. With two arguments, of which the second is a `{', the
first argument gives an account name, and the following lines
create a group of commands for that account until a line
containing a single `}' appears. With one argument, the
previously created group of commands for the account name is
executed, and a folder command is executed for the system mailbox
or inbox of that account. Without arguments, the list of
accounts and their contents are printed. As an example,
account myisp {
set folder=imaps:// HREF=mailto:mylogin@imap.myisp.example>mylogin@imap.myisp.example
set record=+Sent
set from="myname@myisp.example (My Name)"
set smtp=smtp.myisp.example
}
creates an account named `myisp' which can later be selected by
specifying `account myisp'.
alias
(a) With no arguments, prints out all currently-defined aliases.
With one argument, prints out that alias. With more than one
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argument, creates a new alias or changes an old one.
alternates
(alt) The alternates command is useful if the user has accounts
on several machines. It can be used to inform nail that the
listed addresses all belong to the invoking user. When he
replies to messages, nail will not send a copy of the message to
any of the addresses listed on the alternates list. If the
alternates command is given with no argument, the current set of
alternate names is displayed.
answered
(ans) Takes a message list and marks each message as a having
been answered. This mark has no technical meaning in the mail
system; it just causes messages to be marked in the header
summary, and makes them specially addressable.
cache
Only applicable to cached IMAP mailboxes; takes a message list
and reads the specified messages into the IMAP cache.
call Calls a macro (see the define command).
cd Same as chdir.
certsave
Only applicable to S/MIME signed messages. Takes a message list
and a file name and saves the certificates contained within the
message signatures to the named file in both human-readable and
PEM format. The certificates can later be used to send encrypted
messages to the messages' originators by setting the smime-
encrypt-user@host variable.
chdir
(ch) Changes the user's working directory to that specified, if
given. If no directory is given, then changes to the user's
login directory.
classify
(cl) Takes a list of messages and examines their contents for
characteristics of junk mail using Bayesian filtering. Messages
considered to be junk are then marked as such. The junk mail
database is not changed.
collapse
(coll) Only applicable to threaded mode. Takes a message list
and makes all replies to these messages invisible in header
summaries, unless they are in state `new'.
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connect
(conn) If operating in disconnected mode on an IMAP mailbox,
switch to online mode and connect to the mail server while
retaining the mailbox status. See the description of the
disconnected variable for more information.
copy (c) The copy command does the same thing that save does, except
that it does not mark the messages it is used on for deletion
when the user quits. Compressed files and IMAP mailboxes are
handled as described for the folder command.
Copy (C) Similar to copy, but saves the messages in a file named after
the local part of the sender address of the first message.
decrypt
(dec) For unencrypted messages, this command is identical to
copy. Encrypted messages are first decrypted, if possible, and
then copied.
Decrypt
(Dec) Similar to decrypt, but saves the messages in a file named
after the local part of the sender address of the first message.
define
(def) Defines a macro. A macro definition is a sequence of
commands in the following form:
define name {
command1
command2
...
commandN
}
Once defined, a macro can be explicitly invoked using the call
command, or can be implicitly invoked by setting the folder-hook
or folder-hook-fullname variables.
defines
Prints the currently defined macros including their contents.
delete
(d) Takes a list of messages as argument and marks them all as
deleted. Deleted messages will not be saved in mbox, nor will
they be available for most other commands.
discard
Same as ignore.
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disconnect
(disco) If operating in online mode on an IMAP mailbox, switch to
disconnected mode while retaining the mailbox status. See the
description of the disconnected variable for more information. A
list of messages may optionally be given as argument; the
respective messages are then read into the cache before the
connection is closed. Thus `disco *' makes the entire current
mailbox available for disconnected use.
dp or dt
Deletes the current message and prints the next message. If
there is no next message, nail says `at EOF'.
draft
Takes a message list and marks each message as a draft. This
mark has no technical meaning in the mail system; it just causes
messages to be marked in the header summary, and makes them
specially addressable.
echo Echoes its arguments, resolving special names as documented for
the folder command. The escape sequences `\a', `\b', `\c', `\f',
`\n', `\r', `\t', `\v', `\\', and `\0num' are interpreted as with
the echo(1) command.
edit (e) Takes a list of messages and points the text editor at each
one in turn. Modified contents are discarded unless the
writebackedited variable is set.
else Marks the end of the then-part of an if statement and the
beginning of the part to take effect if the condition of the if
statement is false.
endif
Marks the end of an if statement.
exit (ex or x) Effects an immediate return to the Shell without
modifying the user's system mailbox, his mbox file, or his edit
file in -f.
file (fi) The same as folder.
flag (fl) Takes a message list and marks the messages as `flagged' for
urgent/special attention. This mark has no technical meaning in
the mail system; it just causes messages to be highlighted in the
header summary, and makes them specially addressable.
folders
With no arguments, list the names of the folders in the folder
directory. With an existing folder as an argument, lists then
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names of folders below the named folder; e.g. the command
`folders @' lists the folders on the base level of the current
IMAP server. See also the imap-list-depth variable.
folder
(fold) The folder command switches to a new mail file or folder.
With no arguments, it tells the user which file he is currently
reading. If an argument is given, it will write out changes
(such as deletions) the user has made in the current file and
read in the new file. Some special conventions are recognized
for the name. # means the previous file, % means the invoking
user's system mailbox, %user means user's system mailbox, & means
the invoking user's mbox file, and +file means a file in the
folder directory. %:filespec expands to the same value as
filespec, but the file is handled as a system mailbox e. g. by
the mbox and save commands. If the name matches one of the
strings defined with the shortcut command, it is replaced by its
long form and expanded. If the name ends with .gz or .bz2, it is
treated as compressed with gzip(1) or bzip2(1), respectively.
Likewise, if name does not exist, but either name.gz or name.bz2
exists, the compressed file is used. If name refers to a
directory with the subdirectories `tmp', `new', and `cur', it is
treated as a folder in maildir format. A name of the form
protocol://[user@]host[:port][/file]
is taken as an Internet mailbox specification. The supported
protocols are currently imap (IMAP v4r1), imaps (IMAP with
SSL/TLS encryption), pop3 (POP3), and pop3s (POP3 with SSL/TLS
encryption). If user contains special characters, in particular
`/' or `%', they must be escaped in URL notation, as `%2F' or
`%25'. The optional file part applies to IMAP only; if it is
omitted, the default `INBOX' is used. If nail is connected to an
IMAP server, a name of the form @mailbox refers to the mailbox on
that server. If the `folder' variable refers to an IMAP account,
the special name `%' selects the `INBOX' on that account.
Followup
(F) Similar to Respond, but saves the message in a file named
after the local part of the first recipient's address.
followup
(fo) Similar to respond, but saves the message in a file named
after the local part of the first recipient's address.
followupall
Similar to followup, but responds to all recipients regardless of
the flipr and Replyall variables.
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followupsender
Similar to Followup, but responds to the sender only regardless
of the flipr and Replyall variables.
forward
(fwd) Takes a message and the address of a recipient and forwards
the message to him. The text of the original message is included
in the new one, with the value of the fwdheading variable printed
before. The fwdignore and fwdretain commands specify which
header fields are included in the new message. Only the first
part of a multipart message is included unless the forward-as-
attachment option is set.
Forward
(Fwd) Similar to forward, but saves the message in a file named
after the local part of the recipient's address.
from (f) Takes a list of messages and prints their message headers,
piped through the pager if the output does not fit on the screen.
fwdignore
Specifies which header fields are to be ignored with the forward
command. This command has no effect when the forward-as-
attachment option is set.
fwdretain
Specifies which header fields are to be retained with the forward
command. fwdretain overrides fwdignore. This command has no
effect when the forward-as-attachment option is set.
good (go) Takes a list of messages and marks all of them as not being
junk mail. Data from these messages is then inserted into the
junk mail database for future classification.
headers
(h) Lists the current range of headers, which is an 18-message
group. If a `+' argument is given, then the next 18-message
group is printed, and if a `-' argument is given, the previous
18-message group is printed.
help A synonym for ?.
hold (ho, also preserve) Takes a message list and marks each message
therein to be saved in the user's system mailbox instead of in
mbox. Does not override the delete command. nail deviates from
the POSIX standard with this command, as a `next' command issued
after `hold' will display the following message, not the current
one.
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if Commands in nail's startup files can be executed conditionally
depending on whether the user is sending or receiving mail with
the if command. For example:
if receive
commands . . .
endif
An else form is also available:
if receive
commands . . .
else
commands . . .
endif
Note that the only allowed conditions are receive, send, and term
(execute command if standard input is a tty).
ignore
Add the list of header fields named to the ignored list. Header
fields in the ignore list are not printed on the terminal when a
message is printed. This command is very handy for suppression
of certain machine-generated header fields. The Type and Print
commands can be used to print a message in its entirety,
including ignored fields. If ignore is executed with no
arguments, it lists the current set of ignored fields.
imap Sends command strings directly to the current IMAP server. Nail
operates always in IMAP selected state on the current mailbox;
commands that change this will produce undesirable results and
should be avoided. Useful IMAP commands are:
create
Takes the name of an IMAP mailbox as an argument and creates
it.
getquotaroot
Takes the name of an IMAP mailbox as an argument and prints
the quotas that apply to the mailbox. Not all IMAP servers
support this command.
namespace
Takes no arguments and prints the Personal Namespaces, the
Other User's Namespaces, and the Shared Namespaces. Each
namespace type is printed in parentheses; if there are
multiple namespaces of the same type, inner parentheses
separate them. For each namespace, a namespace prefix and a
hierarchy separator is listed. Not all IMAP servers support
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this command.
inc Same as newmail.
junk (j) Takes a list of messages and marks all of them as junk mail.
Data from these messages is then inserted into the junk mail
database for future classification.
kill (k) Takes a list of messages and `kills' them. Killed messages
are not printed in header summaries, and are ignored by the next
command. The kill command also sets the score of the messages to
negative infinity, so that subsequent score commands will not
unkill them again. Killing is only effective for the current
session on a folder; when it is quit, all messages are
automatically unkilled.
list Prints the names of all available commands.
Mail (M) Similar to mail, but saves the message in a file named after
the local part of the first recipient's address.
mail (m) Takes as argument login names and distribution group names
and sends mail to those people.
mbox Indicate that a list of messages be sent to mbox in the user's
home directory when nail is quit. This is the default action for
messages if unless the hold option is set. nail deviates from
the POSIX standard with this command, as a `next' command issued
after `mbox' will display the following message, not the current
one.
move (mv) Acts like copy, but marks the messages for deletion if they
were transferred successfully.
Move (Mv) Similar to move, but moves the messages to a file named
after the local part of the sender address of the first message.
newmail
Checks for new mail in the current folder without committing any
changes before. If new mail is present, a message is printed.
If the header variable is set, the headers of each new message
are also printed.
next (n) like + or CR) Goes to the next message in sequence and types
it. With an argument list, types the next matching message.
New Same as unread.
new Same as unread.
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online
Same as connect.
noop If the current folder is located on an IMAP or POP3 server, a
NOOP command is sent. Otherwise, no operation is performed.
Pipe (Pi) Like pipe but also pipes ignored header fields and all parts
of MIME multipart/alternative messages.
pipe (pi) Takes a message list and a shell command and pipes the
messages through the command. Without an argument, the current
message is piped through the command given by the cmd variable.
If the page variable is set, every message is followed by a
formfeed character.
preserve
(pre) A synonym for hold.
Print
(P) Like print but also prints out ignored header fields and all
parts of MIME multipart/alternative messages. See also print,
ignore, and retain.
print
(p) Takes a message list and types out each message on the user's
terminal. If the message is a MIME multipart message, all parts
with a content type of `text' or `message' are shown, the other
are hidden except for their headers. Messages are decrypted and
converted to the terminal character set if necessary.
probability
(prob) For each word given as argument, the contents of its junk
mail database entry are printed.
quit (q) Terminates the session, saving all undeleted, unsaved
messages in the user's mbox file in his login directory,
preserving all messages marked with hold or preserve or never
referenced in his system mailbox, and removing all other messages
from his system mailbox. If new mail has arrived during the
session, the message `You have new mail' is given. If given
while editing a mailbox file with the -f flag, then the edit file
is rewritten. A return to the Shell is effected, unless the
rewrite of edit file fails, in which case the user can escape
with the exit command.
redirect
(red) Same as resend.
Redirect
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(Red) Same as Resend.
remove
(rem) Removes the named folders. The user is asked for
confirmation in interactive mode.
rename
(ren) Takes the name of an existing folder and the name for the
new folder and renames the first to the second one. Both folders
must be of the same type and must be located on the current
server for IMAP.
Reply
(R) Reply to originator. Does not reply to other recipients of
the original message.
reply
(r) Takes a message list and sends mail to the sender and all
recipients of the specified message. The default message must
not be deleted.
replyall
Similar to reply, but responds to all recipients regardless of
the flipr and Replyall variables.
replysender
Similar to Reply, but responds to the sender only regardless of
the flipr and Replyall variables.
Resend
Like resend, but does not add any header lines. This is not a
way to hide the sender's identity, but useful for sending a
message again to the same recipients.
resend
Takes a list of messages and a user name and sends each message
to the named user. `Resent-From:' and related header fields are
prepended to the new copy of the message.
Respond
Same as Reply.
respond
Same as reply.
respondall
Same as replyall.
respondsender
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Same as replysender.
retain
Add the list of header fields named to the retained list. Only
the header fields in the retain list are shown on the terminal
when a message is printed. All other header fields are
suppressed. The Type and Print commands can be used to print a
message in its entirety. If retain is executed with no
arguments, it lists the current set of retained fields.
Save (S) Similar to save, but saves the messages in a file named after
the local part of the sender of the first message instead of
taking a filename argument.
save (s) Takes a message list and a filename and appends each message
in turn to the end of the file. If no filename is given, the
mbox file is used. The filename in quotes, followed by the line
count and character count is echoed on the user's terminal. If
editing a system mailbox, the messages are marked for deletion.
Compressed files and IMAP mailboxes are handled as described for
the -f command line option above.
savediscard
Same as saveignore.
saveignore
Saveignore is to save what ignore is to print and type. Header
fields thus marked are filtered out when saving a message by save
or when automatically saving to mbox. This command should only
be applied to header fields that do not contain information
needed to decode the message, as MIME content fields do. If
saving messages on an IMAP account, ignoring fields makes it
impossible to copy the data directly on the server, thus
operation usually becomes much slower.
saveretain
Saveretain is to save what retain is to print and type. Header
fields thus marked are the only ones saved with a message when
saving by save or when automatically saving to mbox. Saveretain
overrides saveignore. The use of this command is strongly
discouraged since it may strip header fields that are needed to
decode the message correctly.
score
(sc) Takes a message list and a floating point number and adds
the number to the score of each given message. All messages
start at score 0 when a folder is opened. When the score of a
message becomes negative, it is `killed' with the effects
described for the kill command; otherwise if it was negative
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before and becomes positive, it is `unkilled'. Scores only refer
to the currently opened instance of a folder.
set (se) With no arguments, prints all variable values, piped through
the pager if the output does not fit on the screen. Otherwise,
sets option. Arguments are of the form option=value (no space
before or after =) or option. Quotation marks may be placed
around any part of the assignment statement to quote blanks or
tabs, i.e. `set indentprefix="->"'. If an argument begins with
no, as in `set nosave', the effect is the same as invoking the
unset command with the remaining part of the variable (`unset
save').
seen Takes a message list and marks all messages as having been read.
shell
(sh) Invokes an interactive version of the shell.
shortcut
Defines a shortcut name and its string for expansion, as
described for the folder command. With no arguments, a list of
defined shortcuts is printed.
show (Sh) Like print, but performs neither MIME decoding nor
decryption so that the raw message text is shown.
size Takes a message list and prints out the size in characters of
each message.
sort Create a sorted representation of the current folder, and change
the next command and the addressing modes such that they refer to
messages in the sorted order. Message numbers are the same as in
regular mode. If the header variable is set, a header summary in
the new order is also printed. Possible sorting criteria are:
date Sort the messages by their `Date:' field, that is by the
time they were sent.
from Sort messages by the value of their `From:' field, that is
by the address of the sender. If the showname variable is
set, the sender's real name (if any) is used.
size Sort the messages by their size.
score
Sort the messages by their score.
status
Sort the messages by their message status (new, read, old,
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etc.).
subject
Sort the messages by their subject.
thread
Create a threaded order, as with the thread command.
to Sort messages by the value of their `To:' field, that is by
the address of the recipient. If the showname variable is
set, the recipient's real name (if any) is used.
If no argument is given, the current sorting criterion is
printed.
source
The source command reads commands from a file.
thread
(th) Create a threaded representation of the current folder, i.e.
indent messages that are replies to other messages in the header
display, and change the next command and the addressing modes
such that they refer to messages in the threaded order. Message
numbers are the same as in unthreaded mode. If the header
variable is set, a header summary in threaded order is also
printed.
top Takes a message list and prints the top few lines of each. The
number of lines printed is controlled by the variable toplines
and defaults to five.
touch
Takes a message list and marks the messages for saving in the
mbox file. nail deviates from the POSIX standard with this
command, as a `next' command issued after `mbox' will display the
following message, not the current one.
Type (T) Identical to the Print command.
type (t) A synonym for print.
unalias
Takes a list of names defined by alias commands and discards the
remembered groups of users. The group names no longer have any
significance.
unanswered
Takes a message list and marks each message as not having been
answered.
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uncollapse
(unc) Only applicable to threaded mode. Takes a message list and
makes the message and all replies to it visible in header
summaries again. When a message becomes the current message, it
is automatically made visible. Also when a message with
collapsed replies is printed, all of these are automatically
uncollapsed.
undef
Undefines each of the named macros. It is not an error to use a
name that does not belong to one of the currently defined macros.
undelete
(u) Takes a message list and marks each message as not being
deleted.
undraft
Takes a message list and marks each message as a draft.
unflag
Takes a message list and marks each message as not being
`flagged'.
unfwdignore
Removes the header field names from the list of ignored fields
for the forward command.
unfwdretain
Removes the header field names from the list of retained fields
for the forward command.
ungood
Takes a message list and undoes the effect of a good command that
was previously applied on exactly these messages.
unignore
Removes the header field names from the list of ignored fields.
unjunk
Takes a message list and undoes the effect of a junk command that
was previously applied on exactly these messages.
unkill
Takes a message list and `unkills' each message. Also sets the
score of the messages to 0.
Unread
Same as unread.
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unread
(U) Takes a message list and marks each message as not having
been read.
unretain
Removes the header field names from the list of retained fields.
unsaveignore
Removes the header field names from the list of ignored fields
for saving.
unsaveretain
Removes the header field names from the list of retained fields
for saving.
unset
Takes a list of option names and discards their remembered
values; the inverse of set.
unshortcut
Deletes the shortcut names given as arguments.
unsort
Disable sorted or threaded mode (see the sort and thread
commands), return to normal message order and, if the header
variable is set, print a header summary.
unthread
(unth) Same as unsort.
verify
(verif) Takes a message list and verifies each message. If a
message is not an S/MIME signed message, verification will fail
for it. The verification process checks if the message was
signed using a valid certificate, if the message sender's email
address matches one of those contained within the certificate,
and if the message content has been altered.
visual
(v) Takes a message list and invokes the display editor on each
message. Modified contents are discarded unless the
writebackedited variable is set.
write
(w) For conventional messages, the body without all headers is
written. The output is decrypted and converted to its native
format, if necessary. If the output file exists, the text is
appended.-If a message is in MIME multipart format, its first
part is written to the specified file as for conventional
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messages, and the user is asked for a filename to save each other
part; if the contents of the first part are not to be saved,
`write /dev/null' can be used. If the filename given starts with
a `|' character, the part is piped through the remainder of the
filename interpreted as a shell command. In non-interactive
mode, only the parts of the multipart message that have a
filename given in the part header are written, the other are
discarded. The original message is never marked for deletion in
the originating mail folder. For attachments, the contents of
the destination file are overwritten if the file previously
existed. No special handling of compressed files is performed.
xit (x) A synonym for exit.
z Nail presents message headers in windowfuls as described under
the headers command. The z command scrolls to the next window of
messages. If an argument is given, it specifies the window to
use. A number prefixed by `+' or `-' indicates that the window
is calculated in relation to the current position. A number
without a prefix specifies an absolute window number, and a `$'
lets nail scroll to the last window of messages.
Z Similar to z, but scrolls to the next or previous window that
contains at least one new or `flagged' message.
Tilde escapes
Here is a summary of the tilde escapes, which are used when composing
messages to perform special functions. Tilde escapes are only
recognized at the beginning of lines. The name `tilde escape' is
somewhat of a misnomer since the actual escape character can be set by
the option escape.
~!command
Execute the indicated shell command, then return to the message.
~. Same effect as typing the end-of-file character.
~<filename
Identical to ~r.
~<!command
Command is executed using the shell. Its standard output is
inserted into the message.
~@ [filename . . . ]
With no arguments, edit the attachment list. First, the user can
edit all existing attachment data. If an attachment's file name
is left empty, that attachment is deleted from the list. When
the end of the attachment list is reached, nail will ask for
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further attachments, until an empty file name is given. If
filename arguments are specified, all of them are appended to the
end of the attachment list. Filenames which contain white space
can only be specified with the first method (no filename
arguments).
~A Inserts the string contained in the Sign variable (same as `~i
Sign'). The escape sequences `\t' (tabulator) and `\n' (newline)
are understood.
~a Inserts the string contained in the sign variable (same as `~i
sign'). The escape sequences `\t' (tabulator) and `\n' (newline)
are understood.
~bname . . .
Add the given names to the list of carbon copy recipients but do
not make the names visible in the Cc: line (`blind' carbon copy).
~cname . . .
Add the given names to the list of carbon copy recipients.
~d Read the file `dead.letter' from the user's home directory into
the message.
~e Invoke the text editor on the message collected so far. After
the editing session is finished, the user may continue appending
text to the message.
~fmessages
Read the named messages into the message being sent. If no
messages are specified, read in the current message. Message
headers currently being ignored (by the ignore or retain command)
are not included. For MIME multipart messages, only the first
printable part is included.
~Fmessages
Identical to ~f, except all message headers and all MIME parts
are included.
~h Edit the message header fields `To:', `Cc:', `Bcc:', and
`Subject:' by typing each one in turn and allowing the user to
append text to the end or modify the field by using the current
terminal erase and kill characters.
~H Edit the message header fields `From:', `Reply-To:', `Sender:',
and `Organization:' in the same manner as described for ~h. The
default values for these fields originate from the from, replyto,
and ORGANIZATION variables. If this tilde command has been used,
changing the variables has no effect on the current message
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anymore.
~ivariable
Insert the value of the specified variable into the message
adding a newline character at the end. If the variable is unset
or empty, the message remains unaltered. The escape sequences
`\t' (tabulator) and `\n' (newline) are understood.
~mmessages
Read the named messages into the message being sent, indented by
a tab or by the value of indentprefix. If no messages are
specified, read the current message. Message headers currently
being ignored (by the ignore or retain command) are not included.
For MIME multipart messages, only the first printable part is
included.
~Mmessages
Identical to ~m, except all message headers and all MIME parts
are included.
~p Print out the message collected so far, prefaced by the message
header fields and followed by the attachment list, if any. If
the message text is longer than the screen size, it is piped
through the pager.
~q Abort the message being sent, copying the message to
`dead.letter' in the user's home directory if save is set.
~rfilename
Read the named file into the message.
~sstring
Cause the named string to become the current subject field.
~tname . . .
Add the given names to the direct recipient list.
~v Invoke an alternate editor (defined by the VISUAL option) on the
message collected so far. Usually, the alternate editor will be
a screen editor. After the editor is quit, the user may resume
appending text to the end of the message.
~wfilename
Write the message onto the named file. If the file exists, the
message is appended to it.
~x Same as ~q, except that the message is not saved to the
`dead.letter' file.
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~|command
Pipe the message through the command as a filter. If the command
gives no output or terminates abnormally, retain the original
text of the message. The command fmt(1) is often used as command
to rejustify the message.
~:nail-command
Execute the given nail command. Not all commands, however, are
allowed.
~_nail-command
Identical to ~:.
~~string
Insert the string of text in the message prefaced by a single ~.
If the escape character has been changed, that character must be
doubled in order to send it at the beginning of a line.
Variable options
Options are controlled via set and unset commands, see their entries
for a syntax description. An option is also set if it is passed to
nail as part of the environment (this is not restricted to specific
variables as in the POSIX standard). A value given in a startup file
overrides a value imported from the environment. Options may be
either binary, in which case it is only significant to see whether
they are set or not; or string, in which case the actual value is of
interest.
Binary options
The binary options include the following:
allnet
Causes only the local part to be evaluated when comparing
addresses.
append
Causes messages saved in mbox to be appended to the end rather
than prepended. This should always be set.
ask or asksub
Causes nail to prompt for the subject of each message sent. If
the user responds with simply a newline, no subject field will be
sent.
askatend
Causes the prompts for `Cc:' and `Bcc:' lists to appear after the
message has been edited.
askattach
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If set, nail asks for files to attach at the end of each message.
Responding with a newline indicates not to include an attachment.
askcc
Causes the user to be prompted for additional carbon copy
recipients (at the end of each message if askatend or bsdcompat
is set). Responding with a newline indicates the user's
satisfaction with the current list.
askbcc
Causes the user to be prompted for additional blind carbon copy
recipients (at the end of each message if askatend or bsdcompat
is set). Responding with a newline indicates the user's
satisfaction with the current list.
asksign
Causes the user to be prompted if the message is to be signed at
the end of each message. The smime-sign variable is ignored when
this variable is set.
autocollapse
Causes threads to be collapsed automatically when threaded mode
is entered (see the collapse command).
autoinc
Same as newmail.
autoprint
Causes the delete command to behave like dp - thus, after
deleting a message, the next one will be typed automatically.
autothread
Causes threaded mode (see the thread command) to be entered
automatically when a folder is opened.
bang Enables the substitution of `!' by the contents of the last
command line in shell escapes.
bsdannounce
Causes automatic display of a header summary after executing a
folder command.
bsdcompat
Sets some cosmetical features to traditional BSD style; has the
same affect as setting `askatend' and all other variables
prefixed with `bsd', setting prompt to `& ', and changing the
default pager to more.
bsdflags
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Changes the letters printed in the first column of a header
summary to traditional BSD style.
bsdheadline
Changes the display of columns in a header summary to traditional
BSD style.
bsdmsgs
Changes some informational messages to traditional BSD style.
bsdorder
Causes the `Subject:' field to appear immediately after the `To:'
field in message headers and with the ~h tilde command.
bsdset
Changes the output format of the set command to traditional BSD
style.
chained-junk-tokens
Normally, the Bayesian junk mail filter bases its classifications
on single word tokens extracted from messages. If this option is
set, adjacent words are combined to pairs, which are then used as
additional tokens. This usually improves the accuracy of the
filter, but also increases the junk mail database five- to
tenfold.
datefield
The date in a header summary is normally the date of the mailbox
`From ' line of the message. If this variable is set, the date
as given in the `Date:' header field is used, converted to local
time.
debug
Prints debugging messages and disables the actual delivery of
messages. Unlike verbose, this option is intended for nail
development only.
disconnected
When an IMAP mailbox is selected and this variable is set, no
connection to the server is initiated. Instead, data is obtained
from the local cache (see imap-cache). Mailboxes that are not
present in the cache and messages that have not yet entirely been
fetched from the server are not available; to fetch all messages
in a mailbox at once, the command `copy * /dev/null' can be used
while still in online mode. Changes that are made to IMAP
mailboxes in disconnected mode are queued and committed later
when a connection to that server is opened in online mode. This
procedure is not completely reliable since it cannot be
guaranteed that the IMAP unique identifiers (UIDs) on the server
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still match the ones in the cache at that time. Data is saved to
`dead.letter' when this problem occurs.
disconnected-user@host
The specified account is handled as described for the
disconnected variable above, but other accounts are not affected.
dot The binary option dot causes nail to interpret a period alone on
a line as the terminator of a message the user is sending.
editheaders
When a message is edited while being composed, its header is
included in the editable text. `To:', `Cc:', `Bcc:', `Subject:',
`From:', `Reply-To:', `Sender:', and 'Organization:' fields are
accepted within the header, other fields are ignored.
emptybox
If set, an empty mailbox file is not removed. This may improve
the interoperability with other mail user agents when using a
common folder directory.
emptystart
If the mailbox is empty, nail normally prints `No mail for user'
and exits immediately. If this option is set, nail starts even
with an empty mailbox.
flipr
Exchanges the Respond with the respond commands and vice-versa.
forward-as-attachment
Original messages are normally sent as inline text with the
forward command, and only the first part of a multipart message
is included. With this option, messages are sent as MIME
message/rfc822 attachments, and all of their parts are included.
The fwdignore and fwdretain options are ignored when the
forward-as-attachment option is set.
fullnames
When replying to a message, nail normally removes the comment
parts of email addresses, which by convention contain the full
names of the recipients. If this variable is set, such stripping
is not performed, and comments are retained.
header
Causes the header summary to be written at startup and after
commands that affect the number of messages or the order of
messages in the current folder; enabled by default.
hold This option is used to hold messages in the system mailbox by
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default.
ignore
Causes interrupt signals from the terminal to be ignored and
echoed as @'s.
ignoreeof
An option related to dot is ignoreeof which makes nail refuse to
accept a control-d as the end of a message. Ignoreeof also
applies to nail command mode.
imap-use-starttls
Causes nail to issue a STARTTLS command to make an unencrypted
IMAP session SSL/TLS encrypted. This functionality is not
supported by all servers, and is not used if the session is
already encrypted by the IMAPS method.
imap-use-starttls-user@host
Activates imap-use-starttls for a specific account.
keep This option causes nail to truncate the user's system mailbox
instead of deleting it when it is empty. This should always be
set, since it prevents malicious users from creating fake mail
folders in a world-writable spool directory.
keepsave
When a message is saved, it is usually discarded from the
originating folder when nail is quit. Setting this option causes
all saved message to be retained.
markanswered
When a message is replied to and this variable is set, it is
marked as having been answered. This mark has no technical
meaning in the mail system; it just causes messages to be marked
in the header summary, and makes them specially addressable.
metoo
Usually, when a group is expanded that contains the sender, the
sender is removed from the expansion. Setting this option causes
the sender to be included in the group.
newmail
Checks for new mail in the current folder each time the prompt is
printed. For IMAP mailboxes, the server is then polled for new
mail, which may result in delayed operation if the connection to
the server is slow. A maildir folder must be re-scanned to
determine if new mail has arrived.
If this variable is set to the special value nopoll, an IMAP
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server is not actively asked for new mail, but new mail may still
be detected and announced with any other IMAP command that is
sent to the server. A maildir folder is not scanned then.
In any case, the IMAP server may send notifications about
messages that have been deleted on the server by another process
or client. In this case, `Expunged n messages' is printed
regardless of this variable, and message numbers may have
changed.
noheader
Setting the option noheader is the same as giving the -N flag on
the command line.
outfolder
Causes the filename given in the record variable and the sender-
based filenames for the Copy and Save commands to be interpreted
relative to the directory given in the folder variable rather
than to the current directory unless it is an absolute pathname.
page If set, each message the pipe command prints out is followed by a
formfeed character.
piperaw
Send messages to the pipe command without performing MIME and
character set conversions.
pop3-use-apop
If this variable is set, the APOP authentication method is used
when a connection to a POP3 server is initiated. The advantage
of this method over the usual USER/PASS authentication is that
the password is not sent over the network in clear text. The
connection fails if the server does not support the APOP command.
pop3-use-apop-user@host
Enables pop3-use-apop for a specific account.
pop3-use-starttls
Causes nail to issue a STLS command to make an unencrypted POP3
session SSL/TLS encrypted. This functionality is not supported
by all servers, and is not used if the session is already
encrypted by the POP3S method.
pop3-use-starttls-user@host
Activates pop3-use-starttls for a specific account.
print-all-chars
This option causes all characters to be considered printable. It
is only effective if given in a startup file. With this option
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set, some character sequences in messages may put the user's
terminal in an undefined state when printed; it should only be
used as a last resort if no working system locale can be found.
print-alternatives
When a MIME message part of type multipart/alternative is
displayed and it contains a subpart of type text/plain, other
parts are normally discarded. Setting this variable causes all
subparts to be displayed, just as if the surrounding part was of
type multipart/mixed.
quiet
Suppresses the printing of the version when first invoked.
record-resent
If both this variable and the record variable are set, the resend
and Resend commands save messages to the record folder as it is
normally only done for newly composed messages.
reply-in-same-charset
If this variable is set, nail first tries to use the same
character set of the original message for replies. If this
fails, the sendcharsets variable is evaluated as usual.
Replyall
Reverses the sense of reply and Reply commands.
save When the user aborts a message with two RUBOUT (interrupt
characters) nail copies the partial letter to the file
`dead.letter' in the home directory. This option is set by
default.
searchheaders
If this option is set, then a message-list specifier in the form
`/x:y' will expand to all messages containing the substring `y'
in the header field `x'. The string search is case insensitive.
sendwait
When sending a message, wait until the mail transfer agent exits
before accepting further commands. If the mail transfer agent
returns a non-zero exit status, the exit status of nail will also
be non-zero.
showlast
Setting this option causes nail to start at the last message
instead of the first one when opening a mail folder.
showname
Causes nail to use the sender's real name instead of the plain
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address in the header field summary and in message
specifications.
showto
Causes the recipient of the message to be shown in the header
summary if the message was sent by the user.
smime-force-encryption
Causes nail to refuse sending unencrypted messages.
smime-sign
If this variable is set, outgoing messages are S/MIME signed with
the user's private key. Signing a message enables a recipient to
verify that the sender used a valid certificate, that the email
addresses in the certificate match those in the message header,
and that the message content has not been altered. It does not
change the message text, and people will be able to read the
message as usual.
smime-no-default-ca
Do not load the default CA locations when verifying S/MIME signed
messages. Only applicable if S/MIME support is built using
OpenSSL.
smtp-use-starttls
Causes nail to issue a STARTTLS command to make an SMTP session
SSL/TLS encrypted. Not all servers support this command; because
of common implementation defects, it cannot be automatically
determined whether a server supports it or not.
ssl-no-default-ca
Do not load the default CA locations to verify SSL/TLS server
certificates. Only applicable if SSL/TLS support is built using
OpenSSL.
ssl-v2-allow
Accept SSLv2 connections. These are normally not allowed because
this protocol version is insecure.
stealthmua
Inhibits the generation of the `Message-Id:' and `User-Agent:'
header fields that include obvious references to nail. There are
two pitfalls associated with this: First, the message id of
outgoing messages is not known anymore. Second, an expert may
still use the remaining information in the header to track down
the originating mail user agent.
verbose
Setting the option verbose is the same as using the -v flag on
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the command line. When nail runs in verbose mode, details of the
actual message delivery and protocol conversations for IMAP,
POP3, and SMTP, as well as of other internal processes, are
displayed on the user's terminal, This is sometimes useful to
debug problems. Nail prints all data that is sent to remote
servers in clear texts, including passwords, so care should be
taken that no unauthorized option can view the screen if this
option is enabled.
writebackedited
If this variable is set, messages modified using the edit or
visual commands are written back to the current folder when it is
quit. This is only possible for writable folders in mbox format.
Setting this variable also disables MIME decoding and decryption
for the editing commands.
String Options
The string options include the following:
attrlist
A sequence of characters to print in the `attribute' column of a
header summary, each for one type of messages in the following
order: new, unread but old, new but read, read and old, saved,
preserved, mboxed, flagged, answered, draft, killed, start of a
collapsed thread, collapsed, classified as junk. The default is
`NUROSPMFATK+-J', or `NU *HMFATK+-J' if bsdflags or the SYSV3
environment variable are set.
autobcc
Specifies a list of recipients to which a blind carbon copy of
each outgoing message will be sent automatically.
autocc
Specifies a list of recipients to which a carbon copy of each
outgoing message will be sent automatically.
autosort
Causes sorted mode (see the sort command) to be entered
automatically with the value of this option as sorting method
when a folder is opened.
cmd The default value for the pipe command.
crt The valued option crt is used as a threshold to determine how
long a message must be before PAGER is used to read it. If crt
is set without a value, then the height of the terminal screen
stored in the system is used to compute the threshold (see
stty(1)).
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DEAD The name of the file to use for saving aborted messages. This
defaults to `dead.letter' in the user's home directory.
EDITOR
Pathname of the text editor to use in the edit command and ~e
escape. If not defined, then a default editor is used.
encoding
The default MIME encoding to use in outgoing text messages and
message parts. Valid values are 8bit or quoted-printable. The
default is 8bit. In case the mail transfer system is not ESMTP
compliant, quoted-printable should be used instead. If there is
no need to encode a message, 7bit transfer mode is used, without
regard to the value of this variable. Binary data is always
encoded in base64 mode.
escape
If defined, the first character of this option gives the
character to use in the place of ~ to denote escapes.
folder
The name of the directory to use for storing folders of messages.
All folder names that begin with `+' refer to files below that
directory. If the directory name begins with a `/', nail
considers it to be an absolute pathname; otherwise, the folder
directory is found relative to the user's home directory.
The directory name may also refer to an IMAP account; any names
that begin with `+' then refer to IMAP mailboxes on that account.
An IMAP folder is normally given in the form
imaps:// HREF=mailto:mylogin@imap.myisp.example>mylogin@imap.myisp.example
In this case, the `+' and `@' prefixes for folder names have the
same effect (see the folder command).
Some IMAP servers do not accept the creation of mailboxes in the
hierarchy base; they require that they are created as subfolders
of `INBOX'. With such servers, a folder name of the form
imaps:// HREF=mailto:mylogin@imap.myisp.example>mylogin@imap.myisp.example/INBOX.
should be used (the last character is the server's hierarchy
delimiter). Folder names prefixed by `+' will then refer to
folders below `INBOX', while folder names prefixed by `@' refer
to folders below the hierarchy base. See the imap namespace
command for a method to detect the appropriate prefix and
delimiter.
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folder-hook
When a folder is opened and this variable is set, the macro
corresponding to the value of this variable is executed. The
macro is also invoked when new mail arrives, but message lists
for commands executed from the macro only include newly arrived
messages then.
folder-hook-fullname
When a folder named fullname is opened, the macro corresponding
to the value of this variable is executed. Unlike other folder
specifications, the fully expanded name of a folder, without
metacharacters, is used to avoid ambiguities. The macro
specified with folder-hook is not executed if this variable is
effective for a folder (unless it is explicitly invoked within
the called macro).
from The address (or a list of addresses) to put into the `From:'
field of the message header. If replying to a message, these
addresses are handled as if they were in the alternates list. If
the machine's hostname is not valid at the Internet (for example
at a dialup machine), either this variable or hostname have to be
set to get correct Message-ID header fields. If from contains
more than one address, the sender variable must also be set.
fwdheading
The string to print before the text of a message with the forward
command (unless the forward-as-attachment variable is set).
Defaults to ``-------- Original Message --------'' if unset. If
it is set to the empty string, no heading is printed.
headline
A format string to use for the header summary, similar to printf
formats. A `%' character introduces a format specifier. It may
be followed by a number indicating the field width. If the field
is a number, the width may be negative, which indicates that it
is to be left-aligned. Valid format specifiers are:
lfB4 l. %a Message attributes. %c The score of the
message. %d The date when the message was received.
%e The indenting level in threaded mode. %f The address
of the message sender. %i The message thread structure.
%l The number of lines of the message. %m Message
number. %o The number of octets (bytes) in the message.
%s Message subject (if any). %S Message subject (if any)
in double quotes. %t The position in threaded/sorted
order. %> A `>' for the current message, otherwise ` '.
%< A `<' for the current message, otherwise ` '. %% A
`%' character.
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The default is `%>%a%m %18f %16d %4l/%-5o %i%s', or
`%>%a%m %20f %16d %3l/%-5o %i%S' if bsdcompat is set.
hostname
Use this string as hostname when expanding local addresses
instead of the value obtained from uname(2) and getaddrinfo(3).
imap-auth
Sets the IMAP authentication method. Valid values are `login'
for the usual password-based authentication (the default),
`cram-md5', which is a password-based authentication that does
not send the password over the network in clear text, and
`gssapi' for GSSAPI-based authentication.
imap-auth-user@host
Sets the IMAP authentication method for a specific account.
imap-cache
Enables caching of IMAP mailboxes. The value of this variable
must point to a directory that is either existent or can be
created by nail. All contents of the cache can be deleted by
nail at any time; it is not safe to make assumptions about them.
imap-keepalive
IMAP servers may close the connection after a period of
inactivity; the standard requires this to be at least 30 minutes,
but practical experience may vary. Setting this variable to a
numeric value greater than 0 causes a NOOP command to be sent
each value seconds if no other operation is performed.
imap-list-depth
When retrieving the list of folders on an IMAP server, the
folders command stops after it has reached a certain depth to
avoid possible infinite loops. The value of this variable sets
the maximum depth allowed. The default is 2. If the folder
separator on the current IMAP server is a slash `/', this
variable has no effect, and the folders command does not descend
to subfolders.
indentprefix
String used by the `~m' and `~M' tilde escapes and by the quote
option for indenting messages, in place of the normal tab
character (^I). Be sure to quote the value if it contains spaces
or tabs.
junkdb
The location of the junk mail database. The string is treated
like a folder name, as described for the folder command.
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The files in the junk mail database are normally stored in
compress(1) format for saving space. If processing time is
considered more important, uncompress(1) can be used to store
them in plain form. Nail will then work using the uncompressed
files.
LISTER
Pathname of the directory lister to use in the folders command
when operating on local mailboxes. Default is /bin/ls.
MAIL Is used as the user's mailbox, if set. Otherwise, a system-
dependent default is used. Can be a protocol:// string (see the
folder command for more information).
MAILX_HEAD
A string to put at the beginning of each new message. The escape
sequences `\t' (tabulator) and `\n' (newline) are understood.
MAILX_TAIL
A string to put at the end of each new message. The escape
sequences `\t' (tabulator) and `\n' (newline) are understood.
maximum-unencoded-line-length
Messages that contain lines longer than the value of this
variable are encoded in quoted-printable even if they contain
only ASCII characters. The maximum effective value is 950. If
set to 0, all ASCII text messages are encoded in quoted-
printable. S/MIME signed messages are always encoded in quoted-
printable regardless of the value of this variable.
MBOX The name of the mbox file. It can be the name of a folder. The
default is `mbox' in the user's home directory.
NAIL_EXTRA_RC
The name of an optional startup file to be read after ~/.mailrc.
This variable is ignored if it is imported from the environment;
it has an effect only if it is set in /etc/nail.rc or ~/.mailrc
to allow bypassing the configuration with e. g.
`MAILRC=/dev/null'. Use this file for nail commands that are not
understood by other mailx implementations.
newfolders
If this variable has the value maildir, newly created local
folders will be in maildir format.
nss-config-dir
A directory that contains the files certN.db to retrieve
certificates, keyN.db to retrieve private keys, and secmod.db,
where N is a digit. These are usually taken from Mozilla
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installations, so an appropriate value might be
`~/.mozilla/firefox/default.clm'. Nail opens these files read-
only and does not modify them. However, if the files are
modified by Mozilla while nail is running, it will print a `Bad
database' message. It may be necessary to create copies of these
files that are exclusively used by nail then. Only applicable if
S/MIME and SSL/TLS support is built using Network Security
Services (NSS).
ORGANIZATION
The value to put into the `Organization:' field of the message
header.
PAGER
Pathname of the program to use in the more command or when crt
variable is set. The default paginator pg(1) or, in BSD
compatibility mode, more(1) is used if this option is not
defined.
password-user@host
Set the password for user when connecting to host. If no such
variable is defined for a host, the user will be asked for a
password on standard input. Specifying passwords in a startup
file is generally a security risk, the file should be readable by
the invoking user only.
pipe-content/subcontent
When a MIME message part of content/subcontent type is displayed
or it is replied to, its text is filtered through the value of
this variable interpreted as a shell command. Special care must
be taken when using such commands as mail viruses may be
distributed by this method; if messages of type application/x-sh
were filtered through the shell, for example, a message sender
could easily execute arbitrary code on the system nail is running
on.
pop3-keepalive
POP3 servers may close the connection after a period of
inactivity; the standard requires this to be at least 10 minutes,
but practical experience may vary. Setting this variable to a
numeric value greater than 0 causes a NOOP command to be sent
each value seconds if no other operation is performed.
prompt
The string printed when a command is accepted. Defaults to `? ',
or to `& ' if the bsdcompat variable is set.
quote
If set, nail starts a replying message with the original message
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prefixed by the value of the variable indentprefix. Normally, a
heading consisting of `Fromheaderfield wrote:' is printed before
the quotation. If the string noheading is assigned to the quote
variable, this heading is omitted. If the string headers is
assigned, the headers selected by the ignore/retain commands are
printed above the message body, thus quote acts like an automatic
~m command then. If the string allheaders is assigned, all
headers are printed above the message body, and all MIME parts
are included, thus quote acts like an automatic ~M command then.
record
If defined, gives the pathname of the folder used to record all
outgoing mail. If not defined, then outgoing mail is not so
saved. When saving to this folder fails, the message is not sent
but saved to the `dead.letter' file instead.
replyto
A list of addresses to put into the `Reply-To:' field of the
message header. If replying to a message, such addresses are
handled as if they were in the alternates list.
screen
When nail initially prints the message headers, it determines the
number to print by looking at the speed of the terminal. The
faster the terminal, the more it prints. This option overrides
this calculation and specifies how many message headers are
printed. This number is also used for scrolling with the z
command.
sendcharsets
A comma-separated list of character set names that can be used in
Internet mail. When a message that contains characters not
representable in US-ASCII is prepared for sending, nail tries to
convert its text to each of the given character sets in order and
uses the first appropriate one. The default is `utf-8'.
Character sets assigned to this variable should be ordered in
ascending complexity. That is, the list should start with e.g.
`iso-8859-1' for compatibility with older mail clients, might
contain some other language-specific character sets, and should
end with `utf-8' to handle messages that combine texts in
multiple languages.
sender
An address that is put into the `Sender:' field of outgoing
messages. This field needs not normally be present. It is,
however, required if the `From:' field contains more than one
address. It can also be used to indicate that a message was sent
on behalf of somebody other; in this case, `From:' should contain
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the address of the person that took responsibility for the
message, and `Sender:' should contain the address of the person
that actually sent the message. The sender address is handled as
if it were in the alternates list.
sendmail
To use an alternate mail delivery system, set this option to the
full pathname of the program to use. This should be used with
care.
SHELL
Pathname of the shell to use in the ! command and the ~! escape.
A default shell is used if this option is not defined.
Sign A string for use with the ~A command.
sign A string for use with the ~a command.
signature
Must correspond to the name of a readable file if set. The
file's content is then appended to each singlepart message and to
the first part of each multipart message. Be warned that there
is no possibility to edit the signature for an individual
message.
smime-ca-dir
Specifies a directory with CA certificates for verification of
S/MIME signed messages. The format is the same as described in
SSL_CTX_load_verify_locations(3). Only applicable if S/MIME
support is built using OpenSSL.
smime-ca-file
Specifies a file with CA certificates for verification of S/MIME
signed messages. The format is the same as described in
SSL_CTX_load_verify_locations(3). Only applicable if S/MIME
support is built using OpenSSL.
smime-cipher-user@host
Specifies a cipher to use when generating S/MIME encrypted
messages for user@host. Valid ciphers are rc2-40 (RC2 with 40
bits), rc2-64 (RC2 with 64 bits), des (DES, 56 bits) and des-ede3
(3DES, 112/168 bits). The default is 3DES. It is not
recommended to use the other ciphers unless a recipient's client
is actually unable to handle 3DES since they are comparatively
weak; but even so, the recipient should upgrade his software in
preference.
smime-crl-file
Specifies a file that contains a CRL in PEM format to use when
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verifying S/MIME messages. Only applicable if S/MIME support is
built using OpenSSL.
smime-crl-dir
Specifies a directory that contains files with CRLs in PEM format
to use when verifying S/MIME messages. Only applicable if S/MIME
support is built using OpenSSL.
smime-encrypt-user@host
If this variable is set, messages to user@host are encrypted
before sending. If S/MIME support is built using OpenSSL, the
value of the variable must be set to the name of a file that
contains a certificate in PEM format. If S/MIME support is built
using NSS, the value of this variable is ignored, but if multiple
certificates for user@host are available, the smime-nickname-
user@host variable should be set. Otherwise a certificate for
the recipient is automatically retrieved from the certificate
database, if possible.
If a message is sent to multiple recipients, each of them for
whom a corresponding variable is set will receive an individually
encrypted message; other recipients will continue to receive the
message in plain text unless the smime-force-encryption variable
is set. It is recommended to sign encrypted messages, i.e. to
also set the smime-sign variable.
smime-nickname-user@host
Specifies the nickname of a certificate to be used when
encrypting messages for user@host . Only applicable if S/MIME
support is built using NSS.
smime-sign-cert
Points to a file in PEM format that contains the user's private
key as well as his certificate. Both are used with S/MIME for
signing and decrypting messages. Only applicable if S/MIME
support is built using OpenSSL.
smime-sign-cert-user@host
Overrides smime-sign-cert for the specific addresses. When
signing messages and the value of the from variable is set to
user@host, the specific file is used. When decrypting messages,
their recipient fields (To: and Cc:) are searched for addresses
for which such a variable is set. Nail always uses the first
address that matches, so if the same message is sent to more than
one of the user's addresses using different encryption keys,
decryption might fail. Only applicable if S/MIME support is
built using OpenSSL.
smime-sign-nickname
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Specifies that the named certificate be used for signing mail.
If this variable is not set, but a single certificate matching
the current from address is found in the database, that one is
used automatically. Only applicable if S/MIME support is built
using NSS.
smime-sign-nickname-user@host
Overrides smime-sign-nickname for a specific address. Only
applicable if S/MIME support is built using NSS.
smtp Normally, nail invokes sendmail(8) directly to transfer messages.
If the smtp variable is set, a SMTP connection to the server
specified by the value of this variable is used instead. If the
SMTP server does not use the standard port, a value of
server:port can be given, with port as a name or as a number.
There are two possible methods to get SSL/TLS encrypted SMTP
sessions: First, the STARTTLS command can be used to encrypt a
session after it has been initiated, but before any user-related
data has been sent; see smtp-use-starttls above. Second, some
servers accept sessions that are encrypted from their beginning
on. This mode is configured by assigning smtps://server[:port] to
the smtp variable.
smtp-auth
Sets the SMTP authentication method. If set to `login', or if
unset and both smtp-auth-user and smtp-auth-password are set,
AUTH LOGIN is used. If set to `cram-md5', AUTH CRAM-MD5 is used.
Otherwise, no SMTP authentication is performed.
smtp-auth-user@host
Overrides smtp-auth for specific values of sender addresses,
depending on the from variable.
smtp-auth-password
Sets the global password for SMTP AUTH. Both user and password
have to be given for AUTH LOGIN and AUTH CRAM-MD5.
smtp-auth-password-user@host
Overrides smtp-auth-password for specific values of sender
addresses, depending on the from variable.
smtp-auth-user
Sets the global user name for SMTP AUTH. Both user and password
have to be given for AUTH LOGIN and AUTH CRAM-MD5.
smtp-auth-user-user@host
Overrides smtp-auth-user for specific values of sender addresses,
depending on the from variable.
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ssl-ca-dir
Specifies a directory with CA certificates for verification of
SSL/TLS server certificates. See
SSL_CTX_load_verify_locations(3) for more information. Only
applicable if SSL/TLS support is built using OpenSSL.
ssl-ca-file
Specifies a file with CA certificates for verification of SSL/TLS
server certificates. See SSL_CTX_load_verify_locations(3) for
more information. Only applicable if SSL/TLS support is built
using OpenSSL.
ssl-cert
Sets the file name for a SSL/TLS client certificate required by
some servers. Only applicable if SSL/TLS support is built using
OpenSSL.
ssl-cert-user@host
Sets an account-specific file name for a SSL/TLS client
certificate required by some servers. Overrides ssl-cert for the
specified account. Only applicable if SSL/TLS support is built
using OpenSSL.
ssl-cipher-list
Specifies a list of ciphers for SSL/TLS connections. See
ciphers(1) for more information. Only applicable if SSL/TLS
support is built using OpenSSL.
ssl-crl-file
Specifies a file that contains a CRL in PEM format to use when
verifying SSL/TLS server certificates. Only applicable if
SSL/TLS support is built using OpenSSL.
ssl-crl-dir
Specifies a directory that contains files with CRLs in PEM format
to use when verifying SSL/TLS server certificates. Only
applicable if SSL/TLS support is built using OpenSSL.
ssl-key
Sets the file name for the private key of a SSL/TLS client
certificate. If unset, the name of the certificate file is used.
The file is expected to be in PEM format. Only applicable if
SSL/TLS support is built using OpenSSL.
ssl-key-user@host
Sets an account-specific file name for the private key of a
SSL/TLS client certificate. Overrides ssl-key for the specified
account. Only applicable if SSL/TLS support is built using
OpenSSL.
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ssl-method
Selects a SSL/TLS protocol version; valid values are `ssl2',
`ssl3', and `tls1'. If unset, the method is selected
automatically, if possible.
ssl-method-user@host
Overrides ssl-method for a specific account.
ssl-rand-egd
Gives the pathname to an entropy daemon socket, see RAND_egd(3).
ssl-rand-file
Gives the pathname to a file with entropy data, see
RAND_load_file(3). If the file is a regular file writable by the
invoking user, new data is written to it after it has been
loaded. Only applicable if SSL/TLS support is built using
OpenSSL.
ssl-verify
Sets the action to be performed if an error occurs during SSL/TLS
server certificate validation. Valid values are `strict' (fail
and close connection immediately), `ask' (ask whether to continue
on standard input), `warn' (print a warning and continue),
`ignore' (do not perform validation). The default is `ask'.
ssl-verify-user@host
Overrides ssl-verify for a specific account.
toplines
If defined, gives the number of lines of a message to be printed
out with the top command; normally, the first five lines are
printed.
ttycharset
The character set of the terminal nail operates on. There is
normally no need to set this variable since nail can determine
this automatically by looking at the LC_CTYPE locale setting; if
this succeeds, the value is assigned at startup and will be
displayed by the set command. Note that this is not necessarily
a character set name that can be used in Internet messages.
VISUAL
Pathname of the text editor to use in the visual command and ~v
escape.
ENVIRONMENT VARIABLES
Besides the variables described above, nail uses the following
environment strings:
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HOME The user's home directory.
LANG, LC_ALL, LC_COLLATE, LC_CTYPE, LC_MESSAGES
See locale(7).
MAILRC
Is used as startup file instead of ~/.mailrc if set. When nail
scripts are invoked on behalf of other users, this variable
should be set to `/dev/null' to avoid side-effects from reading
their configuration files.
NAILRC
If this variable is set and MAILRC is not set, it is read as
startup file.
SYSV3
Changes the letters printed in the first column of a header
summary.
TMPDIR
Used as directory for temporary files instead of /tmp, if set.
FILES
~/.mailrc
File giving initial commands.
/etc/nail.rc
System wide initialization file.
~/.mime.types
Personal MIME types.
/etc/mime.types
System wide MIME types.
EXAMPLES
Getting started
The nail command has two distinct usages, according to whether one
wants to send or receive mail. Sending mail is simple: to send a
message to a user whose email address is, say, <bill@host.example>,
use the shell command:
$ nail bill@host.example
then type your message. Nail will prompt you for a message subject
first; after that, lines typed by you form the body of the message.
When you reach the end of the message, type an EOT (control-d) at the
beginning of a line, which will cause nail to echo `EOT' and return
you to the shell.
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If, while you are composing the message you decide that you do not
wish to send it after all, you can abort the letter with a RUBOUT.
Typing a single RUBOUT causes nail to print `(Interrupt -- one more to
kill letter)'. Typing a second RUBOUT causes nail to save your
partial letter on the file dead.letter in your home directory and
abort the letter. Once you have sent mail to someone, there is no way
to undo the act, so be careful.
If you want to send the same message to several other people, you can
list their email addresses on the command line. Thus,
$ nail sam@workstation.example bob@server.example
Subject: Fees
Tuition fees are due next Friday. Don't forget!
<Control-d>
EOT
$
will send the reminder to <sam@workstation.example>. and
<bob@server.example>.
To read your mail, simply type
$ nail
Nail will respond by typing its version number and date and then
listing the messages you have waiting. Then it will type a prompt and
await your command. The messages are assigned numbers starting with
1-you refer to the messages with these numbers. Nail keeps track of
which messages are new (have been sent since you last read your mail)
and read (have been read by you). New messages have an N next to them
in the header listing and old, but unread messages have a U next to
them. Nail keeps track of new/old and read/unread messages by putting
a header field called Status into your messages.
To look at a specific message, use the type command, which may be
abbreviated to simply t . For example, if you had the following
messages:
O 1 drfoo@myhost.example Wed Sep 1 19:52 18/631 "Fees"
O 2 sam@friends.example Thu Sep 2 00:08 30/895
you could examine the first message by giving the command:
type 1
which might cause to respond with, for example:
Message 1:
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From drfoo@myhost.example Wed Sep 1 19:52:25 2004
Subject: Fees
Status: R
Tuition fees are due next Wednesday. Don't forget!
Many nail commands that operate on messages take a message number as
an argument like the type command. For these commands, there is a
notion of a current message. When you enter the nail program, the
current message is initially the first (or the first recent) one.
Thus, you can often omit the message number and use, for example,
t
to type the current message. As a further shorthand, you can type a
message by simply giving its message number. Hence,
1
would type the first message.
Frequently, it is useful to read the messages in your mailbox in
order, one after another. You can read the next message in nail by
simply typing a newline. As a special case, you can type a newline as
your first command to nail to type the first message.
If, after typing a message, you wish to immediately send a reply, you
can do so with the reply command. This command, like type, takes a
message number as an argument. nail then begins a message addressed
to the user who sent you the message. You may then type in your
letter in reply, followed by a <control-d> at the beginning of a line,
as before.
Note that nail copies the subject header from the original message.
This is useful in that correspondence about a particular matter will
tend to retain the same subject heading, making it easy to recognize.
If there are other header fields in the message, like `Cc:', the
information found will also be used.
Sometimes you will receive a message that has been sent to several
people and wish to reply only to the person who sent it. Reply with a
capital R replies to a message, but sends a copy to the sender only.
If you wish, while reading your mail, to send a message to someone,
but not as a reply to one of your messages, you can send the message
directly with the mail command, which takes as arguments the names of
the recipients you wish to send to. For example, to send a message to
<frank@machine.example>, you would do:
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mail frank@machine.example
To delete a message from the mail folder, you can use the delete
command. In addition to not saving deleted messages, nail will not
let you type them, either. The effect is to make the message
disappear altogether, along with its number.
Many features of nail can be tailored to your liking with the set
command. The set command has two forms, depending on whether you are
setting a binary option or a valued option. Binary options are either
on or off. For example, the askcc option informs nail that each time
you send a message, you want it to prompt you for a `Cc:' header, to
be included in the message. To set the askcc option, you would type
set askcc
Valued options are values which nail uses to adapt to your tastes.
For example, the record option tells nail where to save messages sent
by you, and is specified by
set record=Sent
for example. Note that no spaces are allowed in set record=Sent .
Nail includes a simple facility for maintaining groups of messages
together in folders. To use the folder facility, you must tell nail
where you wish to keep your folders. Each folder of messages will be
a single file. For convenience, all of your folders are kept in a
single directory of your choosing. To tell nail where your folder
directory is, put a line of the form
set folder=letters
in your .mailrc file. If, as in the example above, your folder
directory does not begin with a `/', nail will assume that your folder
directory is to be found starting from your home directory.
Anywhere a file name is expected, you can use a folder name, preceded
with `+'. For example, to put a message into a folder with the save
command, you can use:
save +classwork
to save the current message in the classwork folder. If the classwork
folder does not yet exist, it will be created. Note that messages
which are saved with the save command are automatically removed from
your system mailbox.
In order to make a copy of a message in a folder without causing that
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message to be removed from your system mailbox, use the copy command,
which is identical in all other respects to the save command.
The folder command can be used to direct nail to the contents of a
different folder. For example,
folder +classwork
directs nail to read the contents of the classwork folder. All of the
commands that you can use on your system mailbox are also applicable
to folders, including type, delete, and reply. To inquire which
folder you are currently editing, use simply:
folder
To list your current set of folders, use the folders command.
Finally, the help command is available to print out a brief summary of
the most important nail commands.
While typing in a message to be sent to others, it is often useful to
be able to invoke the text editor on the partial message, print the
message, execute a shell command, or do some other auxiliary function.
Nail provides these capabilities through tilde escapes , which consist
of a tilde (~) at the beginning of a line, followed by a single
character which indicates the function to be performed. For example,
to print the text of the message so far, use:
~p
which will print a line of dashes, the recipients of your message, and
the text of the message so far. A list of the most important tilde
escapes is available with `~?'.
IMAP or POP3 client setup
First you need the following data from your ISP: the host name of the
IMAP or POP3 server, user name and password for this server, and a
notice whether the server uses SSL/TLS encryption. Assuming the host
name is `server.myisp.example' and your user name for that server is
`mylogin', you can refer to this account using the folder command or
-f command line option with
imaps:// HREF=mailto:mylogin@server.myisp.example>mylogin@server.myisp.example
(This string is not necessarily the same as your Internet mail
address.) You can replace `imaps://' with `imap://' if the server does
not support SSL/TLS. (If SSL/TLS support is built using NSS, the
nss-config-dir variable must be set before a connection can be
initiated, see above). Use `pop3s://' or `pop3://' if the server does
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not offer IMAP. You should use IMAP if you can, though; first because
it requires fewer network operations than POP3 to get the contents of
the mailbox and is thus faster; and second because message attributes
are maintained by the IMAP server, so you can easily distinguish new
and old messages each time you connect. Even if the server does not
accept IMAPS or POP3S connections, it is possible that it supports the
STARTTLS method to make a session SSL/TLS encrypted after the initial
connection has been performed, but before authentication begins. The
only reliable method to see if this works is to try it; enter one of
set imap-use-starttls
set pop3-use-starttls
before you initiate the connection.
As you probably want messages to be deleted from this account after
saving them, prefix it with `%:'. The shortcut command can be used to
avoid typing that many characters every time you want to connect:
shortcut myisp %:imaps:// HREF=mailto:mylogin@server.myisp.example>mylogin@server.myisp.example
You might want to put this string into a startup file. As the
shortcut command is nail-specific and will confuse other mailx
implementations, it should not be used in ~/.mailrc, instead, put
set NAIL_EXTRA_RC=~/.nailrc
in ~/.mailrc and create a file ~/.nailrc containing the shortcut
command above. You can then access your remote mailbox by invoking
`nail -f myisp' on the command line, or by executing `fi myisp' within
nail.
If you want to use more than one IMAP mailbox on a server, or if you
want to use the IMAP server for mail storage too, the account command
(which is also nail-specific) is more appropriate than the shortcut
command. You can put the following in ~/.nailrc:
account myisp {
set folder=imaps:// HREF=mailto:mylogin@server.myisp.example>mylogin@server.myisp.example
set record=+Sent MBOX=+mbox outfolder
}
and can then access incoming mail for this account by invoking `nail
-A myisp' on the command line, or by executing `ac myisp' within nail.
After that, a command like `copy 1 +otherfolder' will refer to
otherfolder on the IMAP server. In particular, `fi &' will change to
the mbox folder, and `fi +Sent' will show your recorded sent mail,
with both folders located on the IMAP server.
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Nail will ask you for a password string each time you connect to a
remote account. If you can reasonably trust the security of your
workstation, you can give this password in the startup file as
set password-mylogin@server.myisp.example="SECRET"
You should change the permissions of this file to 0600, see chmod(1).
Nail supports different authentication methods for both IMAP and POP3.
If Kerberos is used at your location, you can try to activate GSSAPI-
based authentication by
set imap-auth=gssapi
The advantage of this method is that nail does not need to know your
password at all, nor needs to send sensitive data over the network.
Otherwise, the options
set imap-auth=cram-md5
set pop3-use-apop
for IMAP and POP3, respectively, offer authentication methods that
avoid to send the password in clear text over the network, which is
especially important if SSL/TLS cannot be used. If the server does
not offer any of these authentication methods, conventional
user/password based authentication must be used. It is sometimes
helpful to set the verbose option when authentication problems occur.
Nail will display all data sent to the server in clear text on the
screen with this option, including passwords. You should thus take
care that no unauthorized person can look at your terminal when this
option is set.
If you regularly use the same workstation to access IMAP accounts, you
can greatly enhance performance by enabling local caching of IMAP
messages. For any message that has been fully or partially fetched
from the server, a local copy is made and is used when the message is
accessed again, so most data is transferred over the network once
only. To enable the IMAP cache, select a local directory name and put
set imap-cache=~/localdirectory
in the startup file. All files within that directory can be
overwritten or deleted by nail at any time, so you should not use the
directory to store other information.
Once the cache contains some messages, it is not strictly necessary
anymore to open a connection to the IMAP server to access them. When
nail is invoked with the -D option, or when the disconnected variable
is set, only cached data is used for any folder you open. Messages
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that have not yet been completely cached are not available then, but
all other messages can be handled as usual. Changes made to IMAP
mailboxes in disconnected mode are committed to the IMAP server next
time it is used in online mode. Synchronizing the local status with
the status on the server is thus partially within your responsibility;
if you forget to initiate a connection to the server again before you
leave your location, changes made on one workstation are not available
on others. Also if you alter IMAP mailboxes from a workstation while
uncommitted changes are still pending on another, the latter data may
become invalid. The same might also happen because of internal server
status changes. You should thus carefully evaluate this feature in
your environment before you rely on it.
Many servers will close the connection after a short period of
inactivity. Use one of
set pop3-keepalive=30
set imap-keepalive=240
to send a keepalive message each 30 seconds for POP3, or each 4
minutes for IMAP.
If you encounter problems connecting to a SSL/TLS server, try the
ssl-rand-egd and ssl-rand-file variables (see the OpenSSL FAQ for more
information) or specify the protocol version with ssl-method. Contact
your ISP if you need a client certificate or if verification of the
server certificate fails. If the failed certificate is indeed valid,
fetch its CA certificate by executing the shell command
$ openssl s_client </dev/null -showcerts -connect \
server.myisp.example:imaps 2>&1 | tee log
(see s_client(1)) and put it into the file specified with ssl-ca-file.
The data you need is located at the end of the certificate chain
within (and including) the `BEGIN CERTIFICATE' and `END CERTIFICATE'
lines. (Note that it is possible to fetch a forged certificate by
this method. You can only completely rely on the authenticity of the
CA certificate if you fetch it in a way that is trusted by other
means, such as by personally receiving the certificate on storage
media.)
Creating a score file or message filter
The scoring commands are best separated from other configuration for
clarity, and are mostly nail specific. It is thus recommended to put
them in a separate file that is sourced from your NAIL_EXTRA_RC as
follows:
source ~/.scores
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The .scores file could then look as follows:
define list {
score (subject "important discussion") +10
score (subject "annoying discussion") -10
score (from "nicefellow@goodnet") +15
score (from "badguy@poornet") -5
move (header x-spam-flag "+++++") +junk
}
set folder-hook-imap:// HREF=mailto:user@host>user@host/public.list=list
In this scheme, you would see any mail from `nicefellow@goodnet', even
if the surrounding discussion is annoying; but you normally would not
see mail from `badguy@poornet', unless he participates in the
important discussion. Messages that are marked with five or more plus
characters in their `X-Spam-Flag' field (inserted by some server-side
filtering software) are moved to the folder `junk' in the folder
directory.
Be aware that all criteria in () lead to substring matches, so you
would also score messages from e.g. `notsobadguy@poornetmakers'
negative here. It is possible to select addresses exactly using
"address" message specifications, but these cannot be executed
remotely and will thus cause all headers to be downloaded from IMAP
servers while looking for matches.
When searching messages on an IMAP server, best performance is usually
achieved by sending as many criteria as possible in one large ()
specification, because each single such specification will result in a
separate network operation.
Activating the Bayesian filter
The Bayesian junk mail filter works by examining the words contained
in messages. You decide yourself what a good and what a bad message
is. Thus the resulting filter is your very personal one; once it is
correctly set up, it will filter only messages similar to those
previously specified by you.
To use the Bayesian filter, a location for the junk mail database must
be defined first:
set junkdb=~/.junkdb
The junk mail database does not contain actual words extracted from
messages, but hashed representations of them. A foreign person who
can read the database could only examine the frequency of previously
known words in your mail.
If you have sufficient disk space (several 10 MB) available, it is
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recommended that you set the chained-junk-tokens option. The filter
will then also consider two-word tokens, improving its accuracy.
A set of good messages and junk messages must now be available; it is
also possible to use the incoming new messages for this purpose,
although it will of course take some time until the filter becomes
useful then. Do not underestimate the amount of statistical data
needed; some hundred messages are typically necessary to get
satisfactory results, and many thousand messages for best operation.
You have to pass the good messages to the good command, and the junk
messages to the junk command. If you ever accidentally mark a good
message as junk or vice-versa, call the ungood or unjunk command to
correct this.
Once a reasonable amount of statistics has been collected, new
messages can be classified automatically. The classify command marks
all messages that the filter considers to be junk, but it does not
perform any action on them by default. It is recommended that you
move these messages into a separate folder just for the case that
false positives occur, or to pass them to the junk command later again
to further improve the junk mail database. To automatically move
incoming junk messages every time the inbox is opened, put lines like
the following into your .scores file (or whatever name you gave to the
file in the last example):
define junkfilter {
classify (smaller 20000) :n
move :j +junk
}
set folder-hook-imap:// HREF=mailto:user@host>user@host/INBOX=junkfilter
If you set the verbose option before running the classify command,
nail prints the words it uses for calculating the junk status along
with their statistical probabilities. This can help you to find out
why some messages are not classified as you would like them to be. To
see the statistical probability of a given word, use the probability
command.
If a junk message was not recognized as such, use the junk command to
correct this. Also if you encounter a false positive (a good message
that was wrongly classified as junk), pass it to the good command.
Since the classify command must examine the entire text of all new
messages in the respective folder, this will also cause all of them to
be downloaded from the IMAP server. You should thus restrict the size
of messages for automatic filtering. If server-based filtering is
also available, you might try if that works for you first.
Reading HTML mail
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You need either the w3m or lynx utility or another command-line web
browser that can write plain text to standard output.
set pipe-text/html="w3m -dump -T text/html"
or
set pipe-text/html="lynx -dump -force_html /dev/stdin"
will then cause HTML message parts to be converted into a more
friendly form.
Viewing PDF attachments
Most PDF viewers do not accept input directly from a pipe. It is thus
necessary to store the attachment in a temporary file, as with
set pipe-application/pdf="cat >/tmp/nail$$.pdf; \
acroread /tmp/nail$$.pdf; rm /tmp/nail$$.pdf"
Note that security defects are discovered in PDF viewers from time to
time. Automatical command execution like this can compromise your
system security, in particular if you stay not always informed about
such issues.
Signed and encrypted messages with S/MIME
S/MIME provides two central mechanisms: message signing and message
encryption. A signed message contains some data in addition to the
regular text. The data can be used to verify that the message was
sent using a valid certificate, that the sender's address in the
message header matches that in the certificate, and that the message
text has not been altered. Signing a message does not change its
regular text; it can be read regardless of whether the recipient's
software is able to handle S/MIME. It is thus usually possible to
sign all outgoing messages if so desired.-Encryption, in contrast,
makes the message text invisible for all people except those who have
access to the secret decryption key. To encrypt a message, the
specific recipient's public encryption key must be known. It is thus
not possible to send encrypted mail to people unless their key has
been retrieved from either previous communication or public key
directories. A message should always be signed before it is
encrypted. Otherwise, it is still possible that the encrypted message
text is altered.
A central concept to S/MIME is that of the certification authority
(CA). A CA is a trusted institution that issues certificates. For
each of these certificates, it can be verified that it really
originates from the CA, provided that the CA's own certificate is
previously known. A set of CA certificates is usually delivered with
OpenSSL and installed on your system. If you trust the source of your
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OpenSSL software installation, this offers reasonable security for
S/MIME on the Internet. In general, a certificate cannot be more
secure than the method its CA certificate has been retrieved with,
though. Thus if you download a CA certificate from the Internet, you
can only trust the messages you verify using that certificate as much
as you trust the download process.
The first thing you need for participating in S/MIME message exchange
is your personal certificate, including a private key. The
certificate contains public information, in particular your name and
your email address, and the public key that is used by others to
encrypt messages for you, and to verify signed messages they
supposedly received from you. The certificate is included in each
signed message you send. The private key must be kept secret. It is
used to decrypt messages that were previously encrypted with your
public key, and to sign messages.
For personal use, it is recommended that you get a S/MIME certificate
from one of the major CAs on the Internet using your WWW browser.
(Many CAs offer such certificates for free.) You will usually receive
a combined certificate and private key in PKCS#12 format which nail
does not directly accept if S/MIME support is built using OpenSSL. To
convert it to PEM format, use the following shell command:
$ openssl pkcs12 -in cert.p12 -out cert.pem -clcerts \
-nodes
If you omit the -nodes parameter, you can specifiy an additional PEM
pass phrase for protecting the private key. Nail will then ask you
for that pass phrase each time it signs or decrypts a message. You
can then use
set smime-sign-cert-myname@myisp.example=cert.pem
to make this private key and certificate known to nail.
If S/MIME support is built using NSS, the PKCS#12 file must be
installed using Mozilla (provided that nss-config-dir is set
appropriately, see above), and no further action is necessary unless
multiple user certificates for the same email address are installed.
In this case, the smime-sign-nickname variable has to be set
appropriately.
You can now sign outgoing messages. Just use
set smime-sign
to do so.
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From each signed message you send, the recipient can fetch your
certificate and use it to send encrypted mail back to you.
Accordingly if somebody sends you a signed message, you can do the
same. First use the verify command to check the validity of the
certificate. After that, retrieve the certificate and tell nail that
it should use it for encryption:
certsave filename
set smime-encrypt-user@host=filename
If S/MIME support is built using NSS, the saved certificate must be
installed using Mozilla. The value of the smime-encrypt-user@host is
ignored then, but if multiple certificates for the recipient are
available, the smime-nickname-user@host variable must be set.
You should carefully consider if you prefer to store encrypted
messages in decrypted form. If you do, anybody who has access to your
mail folders can read them, but if you do not, you might be unable to
read them yourself later if you happen to lose your private key. The
decrypt command saves messages in decrypted form, while the save,
copy, and move commands leave them encrypted.
Note that neither S/MIME signing nor encryption applies to message
subjects or other header fields. Thus they may not contain sensitive
information for encrypted messages, and cannot be trusted even if the
message content has been verified. When sending signed messages, it
is recommended to repeat any important header information in the
message text.
Using CRLs with S/MIME or SSL/TLS
Certification authorities (CAs) issue certificate revocation lists
(CRLs) on a regular basis. These lists contain the serial numbers of
certificates that have been declared invalid after they have been
issued. Such usually happens because the private key for the
certificate has been compromised, because the owner of the certificate
has left the organization that is mentioned in the certificate, etc.
To seriously use S/MIME or SSL/TLS verification, an up-to-date CRL is
required for each trusted CA. There is otherwise no method to
distinguish between valid and invalidated certificates. Nail
currently offers no mechanism to fetch CRLs, or to access them on the
Internet, so you have to retrieve them by some external mechanism.
If S/MIME and SSL/TLS support are built using OpenSSL, nail accepts
CRLs in PEM format only; CRLs in DER format must be converted, e.g.
with the shell command
$ openssl crl -inform DER -in crl.der -out crl.pem
To tell nail about the CRLs, a directory that contains all CRL files
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(and no other files) must be created. The smime-crl-dir or ssl-crl-
dir variables, respectively, must then be set to point to that
directory. After that, nail requires a CRL to be present for each CA
that is used to verify a certificate.
If S/MIME and SSL/TLS support are built using NSS, CRLs can be
imported in Mozilla applications (provided that nss-config-dir is set
appropriately).
Sending mail from scripts
If you want to send mail from scripts, you must be aware that nail
reads the user's configuration files by default. So unless your
script is only intended for your own personal use (as e.g. a cron
job), you need to circumvent this by invoking nail like
MAILRC=/dev/null nail -n
You then need to create a configuration for nail for your script.
This can be done by either pointing the MAILRC variable to a custom
configuration file, or by passing the configuration in environment
variables. Since many of the configuration options are not valid
shell variables, the env command is useful in this situation. An
invocation could thus look like
env MAILRC=/dev/null from=scriptreply@domain smtp=host \
smtp-auth-user=login smtp-auth-password=secret \
smtp-auth=login nail -n -s "subject" \
-a attachment_file recipient@domain <content_file
SEE ALSO
fmt(1), newaliases(1), openssl(1), pg(1), more(1), vacation(1),
ssl(3), aliases(5), locale(7), mailaddr(7), sendmail(8)
NOTES
Variables in the environment passed to nail cannot be unset.
The character set conversion relies on the iconv(3) function. Its
functionality differs widely between the various system environments
nail runs on. If the message `Cannot convert from a to b' appears,
either some characters within the message header or text are not
appropriate for the currently selected terminal character set, or the
needed conversion is not supported by the system. In the first case,
it is necessary to set an appropriate LC_CTYPE locale (e.g. en_US) or
the ttycharset variable. In the second case, the sendcharsets and
ttycharset variables must be set to the same value to inhibit
character set conversion. If iconv() is not available at all, the
value assigned to sendcharsets must match the character set that is
used on the terminal.
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Nail expects input text to be in Unix format, with lines separated by
newline (^J, \n) characters only. Non-Unix text files that use
carriage return (^M, \r) characters in addition will be treated as
binary data; to send such files as text, strip these characters e. g.
by
tr -d '\015' <input | nail . . .
or fix the tools that generate them.
Limitations with IMAP mailboxes are: It is not possible to edit
messages, but it is possible to append them. Thus to edit a message,
create a local copy of it, edit it, append it, and delete the
original. The line count for the header display is only appropriate
if the entire message has been downloaded from the server. The
marking of messages as `new' is performed by the IMAP server; use of
the exit command instead of quit will not cause it to be reset, and if
the autoinc/newmail variables are unset, messages that arrived during
a session will not be in state `new' anymore when the folder is opened
again. Also if commands queued in disconnected mode are committed,
the IMAP server will delete the `new' flag for all messages in the
changed folder, and new messages will appear as unread when it is
selected for viewing later. The `flagged', `answered', and `draft'
attributes are usually permanent, but some IMAP servers are known to
drop them without notification. Message numbers may change with IMAP
every time before the prompt is printed if nail is notified by the
server that messages have been deleted by some other client or
process. In this case, `Expunged n messages' is printed, and message
numbers may have changed.
Limitations with POP3 mailboxes are: It is not possible to edit
messages, they can only be copied and deleted. The line count for the
header display is only appropriate if the entire message has been
downloaded from the server. The status field of a message is
maintained by the server between connections; some servers do not
update it at all, and with a server that does, the `exit' command will
not cause the message status to be reset. The `newmail' command and
the `newmail' variable have no effect. It is not possible to rename
or to remove POP3 mailboxes.
If a RUBOUT (interrupt) is typed while an IMAP or POP3 operation is in
progress, nail will wait until the operation can be safely aborted,
and will then return to the command loop and print the prompt again.
When a second RUBOUT is typed while nail is waiting for the operation
to complete, the operation itself will be canceled. In this case,
data that has not been fetched yet will have to be fetched before the
next command can be performed. If the canceled operation was using an
SSL/TLS encrypted channel, an error in the SSL transport will very
likely result, and the connection is no longer usable.
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As nail is a mail user agent, it provides only basic SMTP services.
If it fails to contact its upstream SMTP server, it will not make
further attempts to transfer the message at a later time, and it does
not leave other information about this condition than an error message
on the terminal and a `dead.letter' file. This is usually not a
problem if the SMTP server is located in the same local network as the
computer on which nail is run. However, care should be taken when
using a remote server of an ISP; it might be better to set up a local
SMTP server then which just acts as a proxy.
Nail immediately contacts the SMTP server (or /usr/lib/sendmail) even
when operating in disconnected mode. It would not make much sense for
nail to defer outgoing mail since SMTP servers usually provide much
more elaborated delay handling than nail could perform as a client.
Thus the recommended setup for sending mail in disconnected mode is to
configure a local SMTP server such that it sends outgoing mail as soon
as an external network connection is available again, i.e. to advise
it to do that from a network startup script.
The junk mail filter follows the concepts developed by Paul Graham in
his articles, ``A Plan for Spam'', August 2002,
<http://www.paulgraham.com/spam.html>, and ``Better Bayesian
Filtering'', January 2003, <http://www.paulgraham.com/better.html>.
Chained tokens are due to a paper by Jonathan A. Zdziarski, ``Advanced
Language Classification using Chained Tokens'', February 2004,
<http://www.nuclearelephant.com/papers/chained.html>.
A mail command appeared in Version 1 AT&T Unix. Berkeley Mail was
written in 1978 by Kurt Shoens. This man page is derived from from
The Mail Reference Manual originally written by Kurt Shoens. Nail
enhancements are maintained and documented by Gunnar Ritter.
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information
Technology - Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright c 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE
and The Open Group Standard, the original IEEE and The Open Group
Standard is the referee document. The original Standard can be
obtained online at http://www.opengroup.org/unix/online.html .
Redistribution of this material is permitted so long as this notice
remains intact.
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