MAILX

NAME

mailx − send and receive Internet mail

SYNOPSIS

DESCRIPTION

Mailx 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. Mailx 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 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.

−f [file]

Read in the contents of the user’s mbox (or the specified file) for processing; when mailx is quit, it writes undeleted messages back to this file. The string file is handled as described for the folder command below.

−h hops

Invoke sendmail with the specified hop count. This option has no effect when SMTP is used for sending mail.

−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.

−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).

−S variable[=value]

Sets the internal option variable and, in case of a string option, assigns value to it.

−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.

−u user

Reads the mailbox of the given user name.

Sending mail
To send a message to one or more people, mailx 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 mailx available to help when composing letters.

Reading mail
In normal usage mailx 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 mailx program to forget about the message. This is not irreversible; the message can be undeleted ‘u’) by giving its number, or the mailx 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:

/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. By default, this is a case-sensitive search for the complete email address. If the allnet variable is set, only the local part of the addresses is evaluated for the comparison. Otherwise if the showname variable is set, a case-sensitive search for the complete real name of a sender is performed. The IMAP-style (from address) expression can be used instead if substring matches are desired.

(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, mailx 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)

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.

(senton date)

All messages that were sent on the specified date.

(sentsince date)

All messages that were sent since the specified date.

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, mailx 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 mailx 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 mailx. 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 returned to the machine will have the system wide alias expanded as all mail goes through sendmail.

Recipient address specifications
If the expandaddr option is not set (the default), recipient addresses must be names of local mailboxes or Internet mail addresses.

If the expandaddr option is set, the following rules apply: 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. Mailx 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, mailx 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 mailx. 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
Mailx 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.

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; mailx 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 contain NUL bytes are not converted.

Outgoing attachments are converted 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 mailx 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, mailx 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:

Filenames, where expected, are subjected to the following transformations, in sequence:

The following commands are provided:

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://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’.

alternates

(alt) The alternates command is useful if the user has accounts on several machines. It can be used to inform mailx that the listed addresses all belong to the invoking user. When he replies to messages, mailx 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.

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.

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’.

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.

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 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.

discard

Same as ignore.

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, mailx says ‘at EOF’.

folders

With no arguments, list the names of the folders in the folder directory. With an existing folder as an argument, lists then 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.

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 mailx 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.

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.

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.

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.

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).

create

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 this command.

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.

preserve

(pre) A synonym for hold.

probability

(prob) For each word given as argument, the contents of its junk mail database entry are printed.

redirect

(red) Same as resend.

Redirect

(Red) Same as Resend.

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.

Respond

Same as Reply.

respond

Same as reply.

respondall

Same as replyall.

respondsender

Same as replysender.

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.

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.

date

subject

Sort the messages by their subject.

If no argument is given, the current sorting criterion is printed.

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.

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.

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.

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.

unignore

Removes the header field names from the list of ignored fields.

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.

unshortcut

Deletes the shortcut names given as arguments.

unthread

(unth) Same as unsort.

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.

~<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, mailx will ask for 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).

~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.

~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.

~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.

~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.

~wfilename

Write the message onto the named file. If the file exists, the message is appended to it.

~|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.

~:mailx-command

Execute the given mailx command. Not all commands, however, are allowed.

~_mailx-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 mailx 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:

ask or asksub

Causes mailx 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

If set, mailx asks for files to attach at the end of each message. Responding with a newline indicates not to include an attachment.

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.

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

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.

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.

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 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.

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, mailx normally prints ‘No mail for user’ and exits immediately. If this option is set, mailx starts even with an empty mailbox.

expandaddr

Causes mailx to expand message recipient addresses, as explained in the section, Recipient address specifications.

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, mailx 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.

ignoreeof

An option related to dot is ignoreeof which makes mailx refuse to accept a control-d as the end of a message. Ignoreeof also applies to mailx command mode.

imap-use-starttls

Causes mailx 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.

keepsave

When a message is saved, it is usually discarded from the originating folder when mailx 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.

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 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.

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 mailx 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 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.

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, mailx 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.

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 mailx will also be non-zero.

showlast

Setting this option causes mailx to start at the last message instead of the first one when opening a mail folder.

showname

Causes mailx to use the sender’s real name instead of the plain address in the header field summary and in message specifications.

skipemptybody

If an outgoing message does not contain any text in its first or only message part, do not send it but discard it silently (see also the −E option).

smime-force-encryption

Causes mailx 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 mailx 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 mailx. 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 the command line. When mailx 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. Mailx 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.

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.

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.

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://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://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.

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).

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:

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 mailx. All contents of the cache can be deleted by mailx 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.

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. Mailx will then work using the uncompressed files.

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.

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/mail.rc or ~/.mailrc to allow bypassing the configuration with e. g. ‘MAILRC=/dev/null’. Use this file for 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 installations, so an appropriate value might be ‘~/.mozilla/firefox/default.clm’. Mailx opens these files read-only and does not modify them. However, if the files are modified by Mozilla while mailx is running, it will print a ‘Bad database’ message. It may be necessary to create copies of these files that are exclusively used by mailx 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.

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 mailx 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.

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.

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, mailx 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.

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.

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 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. Mailx 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

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.

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.

The SMTP transfer is executed in a child process; unless either the sendwait or the verbose variable is set, this process runs asynchronously. If it receives a TERM signal, it will abort and save the message to the ‘dead.letter’ file.

smtp-auth

Sets the SMTP authentication method. If set to ‘login’, or if unset and smtp-auth-user is set, AUTH LOGIN is used. If set to ‘cram-md5’, AUTH CRAM-MD5 is used; if set to ‘plain’, AUTH PLAIN 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.

If this variable is set but neither smtp-auth-password or a matching smtp-auth-password-user@host can be found, mailx will as for a password on the user’s terminal.

smtp-auth-user-user@host

Overrides smtp-auth-user for specific values of sender addresses, depending on the from variable.

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.

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 mailx operates on. There is normally no need to set this variable since mailx 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.

ENVIRONMENT VARIABLES

Besides the variables described above, mailx uses the following environment strings:

LANG, LC_ALL, LC_COLLATE, LC_CTYPE, LC_MESSAGES

See locale(7).

FILES

~/.mailrc

File giving initial commands.

/etc/mail.rc

System wide initialization file.

~/.mime.types

Personal MIME types.

/etc/mime.types

System wide MIME types.

EXAMPLES

Getting started
The mailx 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:

$ mailx bill@host.example

then type your message. Mailx 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 mailx to echo ‘EOT’ and return you to the shell.

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 mailx to print ‘(Interrupt -- one more to kill letter)’. Typing a second RUBOUT causes mailx 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,

$ mailx 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

$ mailx

Mailx 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. Mailx 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. Mailx 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 mailx to respond with, for example:

Message 1:
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 mailx 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 mailx 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 mailx by simply typing a newline. As a special case, you can type a newline as your first command to mailx 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. mailx 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 mailx 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:

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, mailx will not let you type them, either. The effect is to make the message disappear altogether, along with its number.

Many features of mailx 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 mailx 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 mailx uses to adapt to your tastes. For example, the record option tells mailx 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 .

Mailx includes a simple facility for maintaining groups of messages together in folders. To use the folder facility, you must tell mailx 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 mailx 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 ‘/’, mailx 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 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 mailx to the contents of a different folder. For example,

folder +classwork

directs mailx 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 mailx 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. Mailx 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://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 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://mylogin@server.myisp.example

You might want to put this string into a startup file. As the shortcut command is specific to this implementation of mailx and will confuse other 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 ‘mailx −f myisp’ on the command line, or by executing ‘fi myisp’ within mailx.

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 mailx-specific) is more appropriate than the shortcut command. You can put the following in ~/.nailrc:

account myisp {
set folder=imaps://mylogin@server.myisp.example
set record=+Sent MBOX=+mbox outfolder
}

and can then access incoming mail for this account by invoking ‘mailx −A myisp’ on the command line, or by executing ‘ac myisp’ within mailx. 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.

Mailx 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).

Mailx 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 mailx 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. Mailx 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 mailx 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 mailx is invoked with the −D option, or when the disconnected variable is set, only cached data is used for any folder you open. Messages 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 mailx specific. It is thus recommended to put them in a separate file that is sourced from your NAIL_EXTRA_RC as follows:

source ~/.scores

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://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 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://user@host/INBOX=junkfilter

If you set the verbose option before running the classify command, mailx 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
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/mailx$$.pdf; \
acroread /tmp/mailx$$.pdf; rm /tmp/mailx$$.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 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 mailx 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. Mailx 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 mailx.

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.

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 mailx 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. Mailx 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, mailx 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 mailx about the CRLs, a directory that contains all CRL files (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, mailx 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 mailx 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 mailx like

MAILRC=/dev/null mailx −n

You then need to create a configuration for mailx 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 mailx −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 mailx cannot be unset.

The character set conversion relies on the iconv(3) function. Its functionality differs widely between the various system environments mailx 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.

Mailx 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 | mailx . . .

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 mailx 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, mailx 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 mailx 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.

As mailx 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 mailx 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.

Mailx immediately contacts the SMTP server (or /usr/lib/sendmail) even when operating in disconnected mode. It would not make much sense for mailx to defer outgoing mail since SMTP servers usually provide much more elaborated delay handling than mailx 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. Heirloom Mailx 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 © 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.