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.\"	@(#)mail.1	8.8 (Berkeley) 4/28/95
.\"
.Dd December 7, 2008
.Dt MAIL 1
.Os
.Sh NAME
.Nm mail ,
.Nm mailx ,
.Nm Mail
.Nd send and receive mail
.Sh SYNOPSIS
.Nm
.Op Fl EIinv
.Op Fl a Ar file
.Op Fl b Ar bcc-addr
.Op Fl c Ar cc-addr
.Op Fl s Ar subject
.Ar to-addr ...
.Op Ar sendmail-flags
.Nm
.Op Fl EIiNnv
.Op Fl H Ns Op colon-modifier
.Fl f
.Op Ar name
.Nm
.Op Fl EIiNnv
.Op Fl H Ns Op colon-modifier
.Op Fl u Ar user
.Sh DESCRIPTION
.Nm
is an intelligent mail processing system, which has
a command syntax reminiscent of
.Xr \&ed 1
with lines replaced by messages.
.Pp
.Bl -tag -width flag
.It Fl a
Attach
.Ar file
to the message.
.It Fl b
Send blind carbon copies to
.Ar list .
List should be a comma-separated list of names.
.It Fl c
Send carbon copies to
.Ar list
of users.
.It Fl E
Don't send messages with an empty body.
This is useful for piping errors from cron scripts.
.It Fl f
Read in the contents of your
.Ar mbox
(or the specified file)
for processing; when you
.Ic quit ,
.Nm
writes undeleted messages back to this file.
.It Fl H
Print the header summaries and exit.
The optional colon-modifier string must begin with a
.Ql \&:
and be followed by one or more of the characters described in the
.Sx Specifying messages
section below.
E.g.,
.Do
.Nm
.Fl H Ns :n
.Dc
will display just new message headers.
.It Fl I
Forces mail to run in interactive mode even when
input isn't a terminal.
In particular, the
.Ic \&~
special
character when sending mail is only active in interactive mode.
.It Fl i
Ignore tty interrupt signals.
This is particularly useful when using
.Nm
on noisy phone lines.
.It Fl N
Inhibits the initial display of message headers
when reading mail or editing a mail folder.
.It Fl n
Inhibits reading
.Pa /etc/mail.rc
upon startup.
.It Fl s
Specify subject on command line
(only the first argument after the
.Fl s
flag is used as a subject; be careful to quote subjects
containing spaces.)
.It Fl u
Is equivalent to:
.Pp
.Dl mail -f /var/mail/user
.It Fl v
Verbose mode.
The details of delivery are displayed on the user's terminal.
.El
.Ss Sending mail
To send a message to one or more people,
.Nm
can be invoked with arguments which are the names of people to
whom the mail will be sent.
You are then expected to type in your message, followed by a
.Ql control-D
at the beginning of a line.
.Pp
Any flags following the list of recipients, will be passed, together
with their arguments, directly to
.Xr sendmail 1 .
For example to change your
.Dv From
address to
.Dv somebody@somewhere.net
you can specify:
.Pp
.Dl mail recipient -f somebody@somewhere.net
.Pp
To prevent multiple copies of a message being sent to the same
address, duplicate addresses (after alias expansion) are removed from
the
.Ar bcc-addr ,
.Ar cc-addr ,
and
.Ar to-addr
lists.
In addition, addresses on the
.Ar cc-addr
and
.Ar to-addr
lists are removed if they occur on the
.Ar bcc-addr
list and addresses on the
.Ar cc-addr
list are removed if they occur on the
.Ar to-addr
list.
If the
.Ar to-addr
list is empty after these deletions, most systems will insert the line
.Dq To: undisclosed recipients:; .
.Pp
The section below
.Sx Replying to or originating mail ,
describes some features of
.Nm
available to help you compose your letter.
.Ss Reading mail
In normal usage
.Nm
is given no arguments and checks your 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
.Ic print
command (which can be abbreviated
.Ic p ) .
You can move among the messages much as you move between lines in
.Xr \&ed 1 ,
with the commands
.Ic \&+
and
.Ic \&\-
moving backwards and forwards, and simple numbers.
.Ss Disposing of mail
After examining a message you can
.Ic delete
.Pq Ic d
the message or
.Ic reply
.Pq Ic r
to it.
Deletion causes the
.Nm
program to forget about the message.
This is not irreversible; the message can be
.Ic undeleted
.Pq Ic u
by giving its number, or the
.Nm
session can be aborted by giving the
.Ic exit
.Pq Ic x
command.
Deleted messages will, however, usually disappear never to be seen again.
.Ss Specifying messages
Many commands (e.g.,
.Ic delete ,
.Ic from ,
and
.Ic print )
accept a list of messages as an argument.
Messages may be specified by their message number, by a range of
messages, or by a pattern string matching certain fields in the header
as described below.
These message
.Dq specs
may be combined by the usual binary boolean operations
.Ql \*[Am] ,
.Ql \&| ,
and
.Ql \&^ ,
which denote, respectively, a logical
.Dq and ,
.Dq or ,
and
.Dq xor .
Logical expressions may be grouped with parentheses
.Ql \&(
and
.Ql \&)
and
negated with
.Ql \&! .
If the binary operator is missing between two message specs, it is
assumed to be a
.Ql \&| .
This is for simplicity, backwards compatibility, and also to to
facilitate using the
.Ql \&|
symbol to denote a pipe.
(See
.Ar enable-pipes . )
.Pp
Besides the obvious (base10) message numbers, the characters
.Ql \&^ ,
.Ql \&- ,
.Ql \&. ,
.Ql \&+ ,
and
.Ql \&$
denote, respectively, the first message, the message before the
.Dq dot
.Pq the current message ,
the
.Dq dot
message, the message following the
.Dq dot ,
and the last message.
.Pp
A
.Dq message range
consists of two message numbers separated by a
.Ql \&- .
A
.Ql \&*
denotes all messages and is equivalent to
.Ql ^-$ .
.Pp
A pattern is a string (not beginning with any of the above special
characters).
If it does not begin with a
.Ql \&/ ,
it is compared with the senders address.
If it begins with a
.Ql \&/ ,
and
.Ar searchheaders
is not defined, the remainder of the string is compared with the
subject field.
(See
.Ar searchheaders
for searching other header fields or the message body.)
If
.Ar regex-search
is not defined, then the comparison is a simple case insensitive
substring match.
(See
.Ar regex-search
for regular expression matches.)
.Pp
A list of messages may be restricted by a
.Dq colon-modifier
string, i.e., a
.Ql \&:
followed by one or more of the characters:
.Bd -literal -offset indent
d	deleted
e	edited
m	mboxed
n	new
o	old
p	preserved
r	read
s	saved
t	tagged
u	unread and not new
!	invert the meaning of the colon-modifiers
.Ed
.Pp
If there are no address specifications other than colon-modifiers,
the colon-modifiers apply to all messages.
Thus
.Dq Li from netbsd :n
would display the headers of all new messages with
.Ql netbsd
in the sender's address, while
.Dq Li from :!r
and
.Dq Li from :nu
would both display all new and unread messages.
Multiple colon-modifiers may be specified and a single
.Ql \&:
with no letters following indicates the colon-modifier from the
preceding command.
.Pp
For example:
.Bd -literal -offset indent
from 1 12 3-5
.Ed
.Pp
would display the headers from messages 1, 3, 4, 5, and 12.
.Bd -literal -offset indent
from anon \*[Am] ( /foo | /bar )
.Ed
.Pp
would display all headers that had
.Ql anon
in the sender's address and either
.Ql foo
or
.Ql bar
in the subject line.
.Pp
Generally, commands cannot select messages that are not displayed,
such as deleted or hidden messages, the exception being the
.Ic undelete
command.
.Ss Replying to or originating mail
You can use the
.Ic reply
command to set up a response to a message, sending it back to the
person who it was from.
Text you then type in, up to an end-of-file,
defines the contents of the message.
While you are composing a message,
.Nm
treats lines beginning with the character
.Ic \&~
specially.
For instance, typing
.Ic \&~m
(alone on a line) will place a copy
of the current message into the response right shifting it by a tab stop
(see
.Em indentprefix
variable, below).
Other escapes will set up subject fields, add and delete recipients
to the message, and allow you 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.)
.Ss Ending a mail processing session
You can end a
.Nm
session with the
.Ic quit
.Pq Ic q
command.
Messages which have been examined go to your
.Ar mbox
file unless they have been deleted in which case they are discarded.
Unexamined messages go back to the post office.
(See the
.Fl f
option above).
.Ss Personal and system wide distribution lists
It is also possible to create a personal distribution lists so that,
for instance, you can send mail to
.Dq Li cohorts
and have it go
to a group of people.
Such lists can be defined by placing a line like
.Pp
.Dl alias cohorts bill ozalp jkf mark kridle@ucbcory
.Pp
in the file
.Pa \&.mailrc
in your home directory.
The current list of such aliases can be displayed with the
.Ic alias
command in
.Nm .
System wide distribution lists can be created by editing
.Pa /etc/mail/aliases ,
see
.Xr aliases 5
and
.Xr sendmail 1 ;
these are kept in a different syntax.
In mail you send, personal aliases will be expanded in mail sent
to others so that they will be able to
.Ic reply
to the recipients.
System wide
.Ic 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
.Xr sendmail 1 .
.Ss Network mail (ARPA, UUCP, Berknet)
See
.Xr mailaddr 7
for a description of network addresses.
.Pp
.Nm
has a number of options which can be set in the
.Pa .mailrc
file to alter its behavior; thus
.Dq Li set askcc
enables the
.Ar askcc
feature.
(These options are summarized below.)
.Sh SUMMARY
(Adapted from the
.Dq Mail Reference Manual )
.Pp
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,
.Nm
types
.Dq Li \&No applicable messages
and aborts the command.
.Bl -tag -width delete
.It Ic \&!
Executes the shell
(see
.Xr sh 1
and
.Xr csh 1 )
command which follows.
.It Ic \&\-
Print out the preceding message.
If given a numeric
argument
.Ar n ,
goes to the
.Ar n Ap th
previous message and prints it.
.It Ic \&=
With no argument, it displays the current message number.
Otherwise, set the current message number to its first argument.
.It Ic \&?
Prints a brief summary of commands.
.It Ic \&|
Pipe the current message body through the shell
(see
.Xr sh 1
and
.Xr csh 1 )
command which follows.
.It Ic Detach
Like
.Ic detach
but also saves MIME parts that don't have a filename associated with
them.
For the unnamed parts, a filename is suggested containing the message
and part numbers, and the subtype.
.It Ic More
.Pq Ic M
Like
.Ic more
but also prints out ignored header fields.
.It Ic Page
.Pq Ic \&Pa
A synonym for
.Ic More .
.It Ic Print
.Pq Ic P
Like
.Ic print
but also prints out ignored header fields.
See also
.Ic print ,
.Ic more ,
.Ic page ,
.Ic type ,
.Ic view ,
.Ic ignore ,
and
.Ic retain .
.It Ic Reply
.Pq Ic R
Reply to originator.
Does not reply to other recipients of the original message.
(See
.Ic reply . )
.It Ic Save
.Pq Ic S
Same as
.Ic save
except that all header fields are saved ignoring the
.Ic saveignore
or
.Ic saveretain
lists.
.It Ic Type
.Pq Ic T
Identical to the
.Ic Print
command.
.It Ic View
.Pq Ic V
Like
.Ic Print
but has the opposite MIME decoding behavior.
(See the
.Ar mime-decode-message
variable.)
.It Ic alias
.Pq Ic a
With no arguments, prints out all currently-defined aliases.
With one argument, prints out that alias.
With more than one argument, creates
a new alias or changes an old one.
.It Ic alternates
.Pq Ic alt
The
.Ic alternates
command is useful if you have accounts on several machines.
It can be used to inform
.Nm
that the listed addresses are really you.
When you
.Ic reply
to messages,
.Nm
will not send a copy of the message to any of the addresses
listed on the
.Ic alternates
list.
If the
.Ic alternates
command is given with no argument, the current set of alternative
names is displayed.
.It Ic bounce
Takes a list of messages and prompts for an address to bounce the
messages to.
If no message is specified, the current message is used.
All the original header fields are preserved except for the
.Ql Delivered-To ,
.Ql X-Original-To
and
.Ql Status
fields.
The new
.Ql To
field contains the bounce address(es) plus any addresses in the old
.Ql To
field minus the user's local address and any on the alternates list.
(See the
.Ic alternates
command.)
.It Ic chdir
.Pq Ic c
Changes the user's working directory to that specified, if given.
If no directory is given, then changes to the user's login directory.
.It Ic copy
.Pq Ic co
The
.Ic copy
command does the same thing that
.Ic save
does, except that it does not mark the messages it
is used on for deletion when you quit.
.It Ic deldups
Delete duplicate messages based on their
.Ql Message-Id
field, keeping the first one in the current sort order.
This can be useful with replies to a mailing list that are also CCed
to a subscriber.
(The same thing can also be accomplished with the threading and
tagging commands.)
.It Ic delete
.Pq Ic d
Takes a list of messages as an argument and marks them all as deleted.
Deleted messages will not be saved in
.Ar mbox ,
nor will they be available for most other commands.
.It Ic detach
Takes a message list followed by a target directory as arguments,
decodes each MIME part in the message list, and saves it in the target
directory.
If the message list is empty, use the current message.
If the directory is not specified, use the directory specified by
.Ar mime-detach-dir
variable and, if that is empty, default to the directory
.Nm
was started in.
For each MIME part in the message list, the filename is displayed for
confirmation or changes.
If an empty name is entered, the part is skipped.
If the filename already exists, the user will be prompted before
overwriting it.
(See the
.Ar mime-detach-batch
and
.Ar mime-detach-overwrite
variables to change this behavior.)
Only MIME parts with an associated filename in the
.Ql Content-Type
or
.Ql Content-Disposition
fields are decoded.
(See
.Ic Detach
to detach all parts.)
The MIME extension hooks and character set conversion are ignored.
.It Ic dp
(also
.Ic dt )
Deletes the current message and prints the next message.
If there is no next message,
.Nm
says
.Dq Li "at EOF" .
.It Ic down
Go down one level in the thread.
If given a message number, it descends the thread below that message,
otherwise it descends from the current message (dot).
.It Ic edit
.Pq Ic e
Takes a list of messages and points the text editor at each one in
turn.
On return from the editor, the message is read back in.
.It Ic else
Switch the command execution condition set by the previous
.Ic if ,
.Ic ifdef ,
or
.Ic ifndef
command.
.It Ic endif
Terminate an
.Ic if ,
.Ic ifdef ,
or
.Ic ifndef
command.
.It Ic exit
.Po Ic ex
or
.Ic x
.Pc
Effects an immediate return to the Shell without
modifying the user's system mailbox, his
.Ar mbox
file, or his edit file in
.Fl f .
.It Ic expose
Expose the thread structure so all messages appear in header listings.
(See
.Ar hide
for the inverse.)
The default header prompt will indent each header line one space for
each level in the threading.
The
.Dq Li "%?* ?"
format string does this.
.It Ic file
.Pq Ic fi
The same as
.Ic folder .
.It Ic flatten
For each message number in the argument list, or the current thread if
no message list is given, promote all exposed children to the same
thread level.
.It Ic folders
List the names of the folders in your folder directory.
.It Ic folder
.Pq Ic fo
The
.Ic folder
command switches to a new mail file or folder.
With no arguments, it tells you which file you are currently reading.
If you give it an argument, it will write out changes (such
as deletions) you have made in the current file and read in
the new file.
Some special conventions are recognized for the name.
.Ql #
means the previous file,
.Ql %
means your system mailbox,
.Ql %user
means user's system mailbox,
.Ql \*[Am]
means your
.Ar mbox
file, and
.Ql +file
means a file in your folder directory.
.It Ic forward
Takes a list of messages and prompts for an address (or addresses) to
forward each message to.
If no message list is specified, the current message is used.
The mail editor is run for each message allowing the user to enter a
message that will precede the forward message.
The message is sent as a multipart/mixed MIME encoded message.
All header fields except the
.Ql Status
field are included.
.It Ic from
.Pq Ic f
Takes a list of messages and prints their message headers.
.It Ic headers
.Pq Ic h
Lists the current range of headers, which is an 18\-message group.
If a
.Ql \&+
argument is given, then the next 18\-message group is printed, and
if a
.Ql \&\-
argument is given, the previous 18\-message group is printed.
.It Ic help
A synonym for
.Ic \&?
.It Ic hide
Collapse the threads so that only the head of each thread is shown,
hiding the subthreads.
(See
.Ar expose
for the inverse.)
.It Ic hidetags
Restrict the display to untagged messages.
In threaded mode, subthreads that connect directly to an untagged
message are also displayed, including tagged messages in the
connecting chain.
.It Ic hidethreads
The same as
.Ar hide .
.It Ic hold
.Po Ic ho ,
also
.Ic preserve
.Pc
Takes a message list and marks each message therein to be saved in
the user's system mailbox instead of in
.Ar mbox .
Does not override the
.Ic delete
command.
.It Ic if
Execute commands that follow depending on the operating mode.
The current supported modes are
.Ql receiving ,
.Ql sending ,
and
.Ql headersonly .
For example, one use might be something like:
.Bd -literal -offset 0
if headersonly
  set header-format="%P%Q%3i %-21.20f %m/%d %R %3K \\"%q\\""
else
  set header-format="%P%Q%?\*[Am] ?%3i %-21.20f %a %b %e %R %3K/%-5O \\"%q\\""
endif
.Ed
.It Ic ifdef
Execute commands that follow if the specified variable is defined.
Note: This includes environment variables.
.It Ic ifndef
Execute commands that follow if the specified variable is not
defined.
.It Ic ignore
Add the list of header fields named to the
.Ar ignored list .
Header fields in the ignore list are not printed
on your terminal when you print a message.
This command is very handy for suppression of certain machine-generated
header fields.
The
.Ic Type
and
.Ic Print
commands can be used to print a message in its entirety, including
ignored fields.
If
.Ic ignore
is executed with no arguments, it lists the current set of
ignored fields.
.It Ic inc
Incorporate any new messages that have arrived while mail
is being read.
The new messages are added to the end of the message list,
and the current message is reset to be the first new mail message.
This does not renumber the existing message list, nor does
it cause any changes made so far to be saved.
.It Ic invtags
Invert the tags on a list of messages or the current message if none
are given.
Note: this will not affect any currently deleted messages.
.It Ic mail
.Pq Ic m
Takes as argument login names and distribution group names and sends
mail to those people.
.It Ic mbox
Indicate that a list of messages be sent to
.Ic mbox
in your home directory when you quit.
This is the default action for messages if you do
.Em not
have the
.Ic hold
option set.
.It Ic mkread
.Pq Ic mk
Takes a message list and marks each message as
having been read.
.It Ic more
.Pq Ic \&mo
Takes a message list and invokes the pager on that list.
.It Ic next
.Pf ( Ic n ,
like
.Ic \&+
or
.Tn CR )
Goes to the next message in sequence and types it.
With an argument list, types the next matching message.
.It Ic page
.Pq Ic pa
A synonym for
.Ic more .
.It Ic preserve
.Pq Ic pre
A synonym for
.Ic hold .
.It Ic print
.Pq Ic p
Takes a message list and types out each message on the user's terminal.
.It Ic quit
.Pq Ic q
Terminates the session, saving all undeleted, unsaved messages in
the user's
.Ar mbox
file in his login directory, preserving all messages marked with
.Ic hold
or
.Ic preserve
or never referenced in his system mailbox, and removing all other
messages from his system mailbox.
If new mail has arrived during the session, the message
.Dq Li "You have new mail"
is given.
If given while editing a mailbox file with the
.Fl f
flag, then the edit file is rewritten.
A return to the Shell is effected, unless the rewrite of edit file
fails, in which case the user can escape with the
.Ic exit
command.
.It Ic reply
.Pq Ic r
Takes a message list and sends mail to the sender and all
recipients of the specified message.
The default message must not be deleted.
(See the
.Ic Reply
command and the
.Ar Replyall
variable.)
.It Ic respond
A synonym for
.Ic reply .
.It Ic retain
Add the list of header fields named to the
.Ar retained list .
Only the header fields in the retained list
are shown on your terminal when you print a message.
All other header fields are suppressed.
The
.Ic Type
and
.Ic Print
commands can be used to print a message in its entirety.
If
.Ic retain
is executed with no arguments, it lists the current set of
retained fields.
.Ic Retain
overrides
.Ic save .
.It Ic reverse
Reverse the order of the messages in at the current thread level.
This is completely equivalent to
.Dq Li sort \&! .
.It Ic save
.Pq Ic s
Takes a message list and a filename and appends each message in
turn to the end of the file.
The filename in quotes, followed by the line
count and character count is echoed on the user's terminal.
.It Ic set
.Pq Ic se
With no arguments, prints all variable values.
Otherwise, sets option.
Arguments are of the form
.Ar option=value
(no space before or after =) or
.Ar option .
Quotation marks may be placed around any part of the assignment
statement to quote blanks or tabs, i.e.
.Dq Li "set indentprefix=\*q-\*[Gt]\*q"
Inside single quotes everything is parsed literally, including
.Sq \e
escaped characters.
Inside double quotes
.Sq \e
character escapes are interpreted.
This is an extension as POSIX specifies that
.Sq \e
should be left uninterpreted for both single and double quoted strings.
.It Ic saveignore
.Ic Saveignore
is to
.Ic save
what
.Ic ignore
is to
.Ic print
and
.Ic type .
Header fields thus marked are filtered out when
saving a message by
.Ic save
or when automatically saving to
.Ar mbox .
.\" .pl +1
.It Ic saveretain
.Ic Saveretain
is to
.Ic save
what
.Ic retain
is to
.Ic print
and
.Ic type .
Header fields thus marked are the only ones saved
with a message when saving by
.Ic save
or when automatically saving to
.Ar mbox .
.Ic Saveretain
overrides
.Ic saveignore .
.It Ic shell
.Pq Ic sh
Invokes an interactive version of the shell.
.It Ic show
.Pq Ic sho
Takes a list of variables and prints out their values in the form
.Ar option=value .
If the list is empty, all variable values are shown.
.It Ic showtags
Display all current messages, tagged or not, unless they are in a
hidden thread.
.It Ic showthreads
The same as
.Ar expose .
.It Ic size
Takes a message list and prints out the size in characters of each
message.
.It Ic smopts
Takes an
.Dq address-spec
followed by the sendmail flags that should be used when sending mail
to an address that matches that
.Dq address-spec .
If no sendmail flags are specified, then list the sendmail flags in
effect for the
.Dq address-spec .
If the
.Dq address-spec
is also omitted, then list all
.Ic smopts
settings.
The
.Dq address-spec
may be an alias, address, domain (beginning with a
.Ql \&@ ) ,
or subdomain
(beginning with a
.Ql \&. ) .
If mail is sent to multiple users, the sendmail flags are
used only if the flags are the same for each recipients.
If
.Ar smopts-verify
is set, then you will be asked to verify the sendmail flags (if there
are any) before the mail is sent.
Address matching is case insensitive and done from most specific to
least.
.Pp
For example if
you have:
.Bd -literal -offset indent
smopts mylist -F "List Maintainer"
smopts @NetBSD.org -f anon@somewhere.net -F "Anon Ymous"
smopts friend@NetBSD.org ""
.Ed
.Pp
then mail sent to any of the addresses that the
.Ql mylist
alias expands to would have the sender's name set to
.Ql List Maintainer .
Mail sent to anyone at NetBSD.org other than
.Ql friend@NetBSD.org
would look like it was sent from
.Ql anon@somewhere.net
by
.Ql Anon Ymous .
Mail sent to
.Ql friend@NetBSD.org
would not have any sendmail flags set (unless they are set by the
.Ic \&~h
escape).
.It Ic sort
With no argument,
.Ic sort
does nothing.
Otherwise it will sort based on the header field name given as an
argument.
A few names are special:
.Bd -literal -offset indent
blines		sort based on the number of body lines.
hlines		sort on the number of header lines.
tlines		sort on the total number of lines.
size		sort on the message size
sday		sent day (ignores the hour/min/sec)
rday		received day (ignores the hour/min/sec)
sdate		sent date
rdate		received date
subject		sort on the subject, ignoring "Re:" prefixes.
from		sort on the sender's address.
.Ed
.Pp
The check for these special names is case sensitive while the header
field name comparisons are case insensitive, so changing the case on
any of these special names will sort based on the header field
ignoring the special keyword.
.Pp
There are also three modifiers which may precede the argument:
.Bd -literal -offset indent
\&!	reverse the sorting order.
\&^	case insensitive sorting.
\&-	skin the field (removing RFC 822 comments and
	keep the address).
.Ed
.Pp
The same keywords and modifiers also apply to threading.
(See the
.Ic thread
command.)
.Pp
Note:
.Ic sort
has no effect on the threading, sorting only on the heads
of the threads if threads exist.
.Pp
.It Ic source
The
.Ic source
command reads commands from a file.
.It Ic tag
Tag a list of messages or the current message if none are given.
In hidden thread mode, the entire thread will be tagged, i.e.,
.Ic tag
is recursive
.It Ic tagbelow
Tag all messages of the current thread below the level of the
current message (dot) or the supplied message number if given.
.It Ic thread
By default this threads the current message list based on the
.Ql In-Reply-To
and
.Ql References
header fields (intended for this purpose by RFC 2822).
If given an argument, it will thread on that header field name
instead.
The same field keywords and modifiers recognized by the sort command
are also recognized here.
Display of the threads is controlled by the
.Ic hide
and
.Ic expose
commands; navigation of threads is done with the
.Ic down ,
.Ic up ,
and
.Ic tset
commands.
.Pp
If
.Ar recursive-commands
is defined, many commands (e.g.,
.Ic print )
act on the entire thread (when it is hidden), otherwise they act on
just the current message.
.Pp
Note: the
.Ql In-Reply-To
and
.Ql Reference
header fields are necessary to do threading correctly.
This version of
.Nm
now emits these header fields when replying.
.It Ic top
Takes a message list and prints the top few lines of each.
The number of lines printed is controlled by the variable
.Ic toplines
and defaults to five.
.It Ic tset
Set the current thread (thread set) so that the supplied message
number (or the current message if no argument is given) is at the top
level of the current thread.
.It Ic type
.Pq Ic t
A synonym for
.Ic print .
.It Ic unalias
Takes a list of names defined by
.Ic alias
commands and discards the remembered groups of users.
The group names no longer have any significance.
.It Ic undelete
.Pq Ic u
Takes a message list and marks each message as
.Ic not
being deleted.
.It Ic unread
.Pq Ic unr
Takes a message list and marks each message as
.Em not
having been read.
.It Ic unset
Takes a list of option names and discards their remembered values;
the inverse of
.Ic set .
.It Ic unsmopts
Takes a list of
.Dq address-specs
defined by
.Ic smopts
commands and discards them from the smopts database.
.It Ic untag
Untag a list of messages or the current message if none are given.
Like the
.Ic tag
command,
.Ic untag
is recursive on hidden threads.
.It Ic unthread
Undo all threading and sorting, restoring the original display order,
i.e., the order in the mail file.
.It Ic up
Go up one level in the thread.
This also takes an optional (positive) argument to go up multiple
levels in the thread.
.It Ic view
.Pq Ic vie
Like
.Ic print
but has the opposite MIME decoding behavior.
(See the
.Ar mime-decode-message
variable.)
.It Ic visual
.Pq Ic v
Takes a message list and invokes the display editor on each message.
.It Ic write
.Pq Ic w
Similar to
.Ic save ,
except that
.Em only
the message body
.Em ( without
the header) is saved.
Extremely useful for such tasks as sending and receiving source
program text over the message system.
.It Ic xit
.Pq Ic x
A synonym for
.Ic exit .
.It Ic z
.Nm
presents message headers in windowfuls as described under the
.Ic headers
command.
You can move
.Nm Ns Ap s
attention forward to the next window with the
.Ic \&z
command.
Also, you can move to the previous window by using
.Ic \&z\&\- .
.El
.Ss 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
.Dq Em tilde\ escape
is somewhat of a misnomer since the actual escape character can be set
by the option
.Ic escape .
.Bl -tag -width Ds
.It Ic \&~! Ns Ar command
Execute the indicated shell command, then return to the message.
.It Ic \&~@ Op Ar filelist
Add the files in the white-space delimited
.Ar filelist
to the attachment list.
If
.Ar filelist
is omitted, edit the attachment list, possibly appending to it: For
each file in the list the user is prompted to change its attachment
data.
Changing the filename to empty will delete it from the list.
Upon reaching the end of the attachment list, the user is prompted for
additional files to attach until an empty filename is given.
Filenames containing white-space can only be added in this
.Dq edit
mode.
.It Ic \&~a
Inserts the autograph string from the sign= option into the message.
.It Ic \&~A
Inserts the autograph string from the Sign= option into the message.
.It Ic \&~b Ns Ar name ...
Add the given names to the list of carbon copy recipients but do not make
the names visible in the Cc: line
.Dq ( blind
carbon copy).
.It Ic \&~c Ns Ar name ...
Add the given names to the list of carbon copy recipients.
.It Ic \&~d
Read the file
.Dq Pa dead.letter
from your home directory into the message.
.It Ic \&~e
Invoke the text editor on the message collected so far.
After the editing session is finished, you may continue appending
text to the message.
.It Ic \&~f Ns Ar messages
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
.Ic ignore
or
.Ic retain
command) are not included.
.It Ic \&~F Ns Ar messages
Identical to
.Ic \&~f ,
except all message headers are included.
.It Ic \&~h
Edit the message header fields, and the options passed to sendmail (the
.Li Smopts ) ,
by typing each one in turn and allowing the user to append text to the
end or modify the field by using the current terminal erase and kill
characters.
If
.Xr editline 3
support is included, then that line editor is used.
.It Ic \&~i Ns Ar string
Inserts the value of the named option into the text of the message.
.It Ic \&~m Ns Ar messages
Read the named messages into the message being sent, indented by a
tab or by the value of
.Ar indentprefix .
If no messages are specified, read the current message.
Message headers currently being ignored (by the
.Ic ignore
or
.Ic retain
command) are not included.
.It Ic \&~M Ns Ar messages
Identical to
.Ic \&~m ,
except all message headers are included.
.It Ic \&~p
Print out the message collected so far, prefaced by the message header
fields.
.It Ic \&~q
Abort the message being sent, copying the message to
.Dq Pa dead.letter
in your home directory if
.Ic save
is set.
.It Ic \&~x
Exits as with \&~q, except the message is not saved in
.Dq Pa dead.letter .
.It Ic \&~r Ns Ar filename
.It Ic \&~\*[Lt] Ns Ar filename
Reads the named file into the message.
If the argument begins with
.Ql \&! ,
the rest of the string is taken as an arbitrary system command and is
executed, with the standard output inserted into the message.
.It Ic \&~s Ns Ar string
Cause the named string to become the current subject field.
.It Ic \&~\&t Ns Ar name ...
Add the given names to the direct recipient list.
.It Ic \&~\&v
Invoke an alternative editor (defined by the
.Ev VISUAL
option) on the message collected so far.
Usually, the alternative editor will be a screen editor.
After you quit the editor, you may resume appending
text to the end of your message.
.It Ic \&~w Ns Ar filename
Write the message onto the named file.
.It Ic \&~\&| Ns Ar command
Pipe the message body through the command as a filter.
If the command gives no output or terminates abnormally, retain the
original text of the message.
The command
.Xr fmt 1
is often used as
.Ic command
to rejustify the message.
.It Ic \&~: Ns Ar mail-command
Execute the given mail command.
Not all commands, however, are allowed.
.It Ic \&~~ Ns Ar string
Insert the string of text in the message prefaced by a single ~.
If you have changed the escape character, then you should double
that character in order to send it.
.El
.Ss Mail Options
Options are controlled via
.Ic set
and
.Ic unset
commands.
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.
The binary options include the following:
.Bl -tag -width append
.It Ar append
Causes messages saved in
.Ar mbox
to be appended to the end rather than prepended.
This should always be set (perhaps in
.Pa /etc/mail.rc ) .
.It Ar ask , Ar asksub
Causes
.Nm
to prompt you for the subject of each message you send.
If you respond with simply a newline, no subject field will be sent.
.It Ar askcc
Causes you to be prompted for additional carbon copy recipients at
the end of each message.
Responding with a newline indicates your
satisfaction with the current list.
.It Ar autoinc
Causes new mail to be automatically incorporated when it arrives.
Setting this is similar to issuing the
.Ic inc
command at each prompt, except that the current message is not
reset when new mail arrives.
.It Ar askbcc
Causes you to be prompted for additional blind carbon copy recipients
at the end of each message.
Responding with a newline indicates your
satisfaction with the current list.
.It Ar autoprint
Causes the
.Ic delete
command to behave like
.Ic dp
\- thus, after deleting a message, the next one will be typed
automatically.
.It Va crt
If
.Va crt
is set, then the
.Ev PAGER
will be used for the
.Ic print ,
.Ic Print ,
.Ic type ,
and
.Ic Type
commands.
Normally these commands do not invoke the pager.
.It Ar debug
Setting the binary option
.Ar debug
is the same as specifying
.Fl d
on the command line and causes
.Nm
to output all sorts of information useful for debugging
.Nm .
.It Ar dot
The binary option
.Ar dot
causes
.Nm
to interpret a period alone on a line as the terminator
of a message you are sending.
.It Ar enable-pipes
If defined, the output of most commands can be piped into a shell
command or redirected to a file.
The pipe/redirection is signaled by the first occurrence of a
.Ql |
or
.Ql \*[Gt]
character that is not in a quoted string or in a parenthetical
group.
This character terminates the mail command line and the remaining
string is passed to the shell.
For example, assuming normal headers, something like
.Bd -literal -offset indent
  from john@ | fgrep -i ' "Re:' | wc
.Ed
.Pp
could be used to count how may replies were made by senders with
.Ql john@
in their address and
.Bd -literal -offset indent
  from john@ \*[Gt]\*[Gt] /tmp/john
.Ed
.Pp
would append all the headers from such senders to /tmp/john.
.Pp
Note: With piping enabled, you cannot use the
.Ql \&|
as a logical
.Dq or
operator outside of a parenthetical group.
This should not be a problem as it is the default logical operator.
(See the
.Sx Specifying messages
section.)
.It Ar hold
This option is used to hold messages in the system mailbox
by default.
.It Ar ignore
Causes interrupt signals from your terminal to be ignored and echoed as
@'s.
.It Ar metoo
Usually, when a group is expanded that contains the sender, the sender
is removed from the expansion.
Setting this option causes the sender to be included in the group.
.It Ar mime-attach-list
If set, the command line flag
.Fl a
will accept a whitespace delimited list of files.
Otherwise, its argument is interpreted as a single filename.
Warning: If enabled, care must be taken to properly quote files that
contain whitespace, both from the shell and from this second expansion
done by
.Nm .
.It Ar mime-decode-header
If set, decode the headers along with the body when
.Ar mime-decode-message
is set.
The header decode follows the same rules as the body (see
.Ar mime-decode-message ) .
.It Ar mime-decode-insert
When inserting
a message into the mail buffer
.Po Ic \&~f
or
.Ic \&~F
.Pc ,
the text inserted will be decoded according to the settings of the
.Ar mime-decode-message
and
.Ar mime-decode-header
variables.
.It Ar mime-decode-message
If set, the
.Ic More ,
.Ic more ,
.Ic Page ,
.Ic page ,
.Ic Print ,
.Ic print ,
.Ic Type ,
and
.Ic type
commands will display decoded the MIME messages.
Otherwise, they display the undecoded message.
Recall that the
.Ic View
and
.Ic view
commands always have the opposite MIME decoding behavior from these
commands.
.It Ar mime-decode-quote
When quoting
a message into the mail buffer
.Po Ic \&~m
or
.Ic \&~M
.Pc ,
the text inserted will be decoded according to the settings of the
.Ar mime-decode-message
and
.Ar mime-decode-header
variables.
.It Ar mime-detach-batch
If set, the detach command does not prompt for anything
.Po unless
.Ar mime-detach-overwrite
is set to
.Ql ask
.Pc ,
overwriting target files depending on the setting of
.Ar mime-detach-overwrite .
.It Ar noheader
Setting the option
.Ar noheader
is the same as giving the
.Fl N
flag on the command line.
.It Ar nosave
Normally, when you abort a message with two
.Tn RUBOUT
(erase or delete)
.Nm
copies the partial letter to the file
.Dq Pa dead.letter
in your home directory.
Setting the binary option
.Ar nosave
prevents this.
.It Ar quiet
Suppresses the printing of the version when first invoked.
.It Ar recursive-commands
When defined, and threading is in effect, the following commands
operate on the entire thread (if it is
.Dq hidden )
rather than just the top displayed message of the thread:
.Bd -literal -offset indent
More Page Print Type View more page print type view
top
Save copy save write
Detach detach
delete dp dt
undelete
hold preserve
mbox mkread touch unread
tag untag invtags
.Ed
.Pp
If not defined, or if the threads are
.Dq exposed ,
commands behave exactly as they do in non-threaded mode, i.e., each
operates on individual messages.
.It Ar Replyall
Reverses the sense of
.Ic reply
and
.Ic Reply
commands.
.It Ar searchheaders
If this option is set, then a message-list specifier in the form
.Dq /x:y
will expand to all messages containing the substring
.Dq y
in the header field
.Dq x .
The string search is case insensitive.
If
.Dq x
is omitted, it will default to the
.Ql Subject
header field.
If
.Dq y
is omitted, only those messages that contain the field
.Dq x
will be matched.
The three forms
.Dq /from:y ,
.Dq /to:y ,
and
.Dq /body:y
are special.
The first will match all messages which contain the substring
.Dq y
in the headline (which is added locally at receipt time and begins
with
.Dq From \& ) .
The second will match all messages containing the substring
.Dq y
in the
.Ql To ,
.Ql Cc ,
or
.Ql Bcc
header fields.
The third will match all messages which contain the substring
.Dq y
in a line of the message body.
The check for
.Dq from ,
.Dq to ,
and
.Dq body
is case sensitive, so that
.Dq /From:y
and
.Dq /To:y
can be used to search the
.Ql From
and
.Ql To
fields, respectively.
(See also
.Ar "regex-search" . )
.It Ar smopts-verify
Verify the sendmail options used on outgoing mail if they were obtained from a
.Ar smopts
match.
This has no effect if there are no sendmail flags or if the flags
were set by the
.Ic \&~h
escape.
.It Ar verbose
Setting the option
.Ar verbose
is the same as using the
.Fl v
flag on the command line.
When mail runs in verbose mode, the actual delivery of messages is
displayed on the user's terminal.
.El
.Ss Option String Values
.Bl -tag -width Va
.It Ev EDITOR
Pathname of the text editor to use in the
.Ic edit
command and
.Ic \&~e
escape.
If not defined, then a default editor is used.
.It Ev LISTER
Pathname of the directory lister to use in the
.Ic folders
command.
Default is
.Pa /bin/ls .
.It Ev PAGER
Pathname of the program to use in the
.Ic more
command or when
.Ic crt
variable is set.
The default paginator
.Xr more 1
is used if this option is not defined.
.It Ev SHELL
Pathname of the shell to use in the
.Ic \&!
command and the
.Ic \&~!
escape.
A default shell is used if this option is not defined.
.It Ev VISUAL
Pathname of the text editor to use in the
.Ic visual
command and
.Ic \&~v
escape.
.It Ar el-completion-keys
A comma or space delimited list of keys to do
.Xr editline 3
completion.
For example
.Nm set el-completion-keys=^I,^D
will bind completion to both the tab and CTRL-D keys.
(Requires
.Xr editline 3
support.)
.It Ar el-editor
The line editing mode: must be
.Ql emacs
or
.Ql vi .
If unset, editing is not enabled.
(Requires
.Xr editline 3
support.)
.It Ar el-history-size
The number of lines of history to remember.
If unset, history is not enable.
(Requires
.Xr editline 3
support.)
.It Ar escape
If defined, the first character of this option gives the character to
use in the place of
.Ic \&~
to denote escapes.
.It Ar folder
The name of the directory to use for storing folders of
messages.
If this name begins with a
.Ql / ,
.Nm
considers it to be an absolute pathname; otherwise, the
folder directory is found relative to your home directory.
.It Ar header-format
If set, use this format string when displaying headers in command
mode.
The format string supports the following conversions in addition to
those of
.Xr strftime 3 :
.Pp
.Bl -tag -width ".Ar \&%?key?" -compact
.It Ar \&%?key?
The header field with name
.Ql key .
Note: if key[0] is
.Ql \&- ,
ignore the
.Ql \&-
and extract the address
portion of the field (i.e.,
.Dq skin
the field).
.It Ar \&%?*string?
If the depth is
.Ar n ,
substitute
.Ql string
.Ar n
times.
This is intended to be used when displaying an
.Dq exposed thread .
.It Ar \&%?\*[Am]string?
Like
.Ar \&%?*string? ,
but uses the depth relative to the current depth rather than the
absolute depth.
.It Ar \&%J
The number of header lines in the message.
.It Ar \&%K
The number of body lines in the message.
.It Ar \&%L
The total number of lines in the message.
.It Ar \&%N
The sender's full name (as in the
.Ql From
or
.Ql Sender
fields).
.It Ar \&%O
The message size.
.It Ar \&%P
The current
.Dq dot
.Pq Sq \*[Gt]
message.
.It Ar \&%Q
The message status flag.
.It Ar \&%Z
The time zone name (if it exists).
.It Ar \&%f
The email address of sender.
.It Ar \&%i
The message number.
.It Ar \&%n
The sender's login name (taken from the address).
.It Ar \&%q
The subject.
.It Ar \&%t
The total number of messages.
.It Ar \&%z
The GMT offset (if found).
.El
.Pp
If the format string begins with
.Ql "\&%??"
then the date will be extracted from the headline.
Otherwise it will be extracted from the
.Ql Date
header falling back to the headline if that extraction fails.
For example, the default format is:
.Bd -literal -offset 0
set header-format=\&"\&%??%P%Q%?* ?%3i \&%-21.20f \&%a \&%b \&%e \&%R \&%3K/%-5O \&\\"%q\\""
.Ed
.Pp
Note 1: The message status flag
.Ql \&%Q
will display the single character
.Ql \+
for the parent of a subthread.
This will be overwritten by a
.Ql T ,
.Ql E ,
.Ql \&* ,
.Ql P ,
.Ql U ,
.Ql N ,
.Ql M
indicating, respectively, a tagged, modified, saved, preserved,
unread, new, or modified message, in that order with the last matching
condition being the one displayed.
In the case of hidden threads, the entire subthread is searched and
the letters above will be displayed in lower case if the property is
that of a hidden child with the case
.Ql \&*
being displayed as
.Ql \*[Am] .
.Pp
Note 2:
.Ar \&%n
and
.Ar \&%t
as used by
.Xr strftime 3
were redundant with \\t and \\n, respectively, so nothing is lost
using them here.
.It Ar ignoreeof
An option related to
.Ar dot
is
.Ar ignoreeof
which makes
.Nm
refuse to accept a
.Ql control-D
as the end of a message.
If given a numeric argument
.Ar n ,
a
.Ql control-D
will be accepted after
.Ar n
tries.
.Ar Ignoreeof
also applies to
.Nm
command mode.
.It Ar indentpreamble
If set, this format string will be inserted before quoting a message
.Po Ic \&~m
or
.Ic \&~M
.Pc .
The format syntax is the same as for
.Ar header-format .
For example, the following:
.Bd -literal -offset 0
set indentpreamble=
  \&"On \&%b \&%e \&%T, \&%Y \&%z (%Z), \&%n (%.50N) wrote:\\n-- Subject: \&%.65q\\n"
.Ed
.Pp
would insert something like
.Bd -literal -offset 0
On Oct 27 11:00:07, 2006 -0400 (EDT), anon (Anon Ymous) wrote:
-- Subject: suggestions for mail(1)
.Ed
.Pp
before the quoted message.
.It Ar indentprefix
String used by the
.Ic ~m
and
.Ic ~M
tilde escapes for indenting messages, in place of
the normal tab character
.Pq Sq ^I .
Be sure to quote the value if it contains
spaces or tabs.
.It Ar indentpostscript
If set, this format string will be inserted after quoting a message
.Po Ic \&~m
or
.Ic \&~M
.Pc .
The format syntax is the same as for
.Ar header-format .
For example, the following:
.Bd -literal -offset 0
set indentpostscript="-- End of excerpt from \&%.50N"
.Ed
.Pp
would insert something like
.Bd -literal -offset 0
-- End of excerpt from Anon Ymous
.Ed
.Pp
after the quoted message.
.It Ar mime-body-TYPE-SUBTYPE
MIME-hook for the body of a MIME block of
.Ql "Content-Type: TYPE/SUBTYPE" .
(See
.Sy MIME Enhancements
below.)
.It Ar mime-charset
Convert
.Ql "Content-type: text"
messages to this character set or
.Ql us-ascii
if the value is empty.
If unset, no character set conversion is done.
.It Ar mime-detach-dir
The directory to detach files to if the
.Ar detach
command is given no arguments.
(See
.Ar detach . )
.It Ar mime-detach-overwrite
This controls overwriting of existing files by the detach command.
If set to
.Ql ask
the user will be prompted before overwriting a file.
If set to
.Ql yes ,
or to the empty string, existing target files will be overwritten.
If set to
.Ql no ,
no target files will be overwritten.
.It Ar mime-encode-message
If set, encode the body of the message as required.
Typically, this is just an issue of whether
.Ql quoted-printable
encoding is used or not.
If it has a value, then use it to determine the encoding type.
Allowed values are
.Ql 7bit ,
.Ql 8bit ,
.Ql binary ,
.Ql quoted-printable ,
or
.Ql base64 .
.It Ar mime-head-TYPE-SUBTYPE
MIME-hook for the header of a MIME block of
.Ql "Content-Type: TYPE/SUBTYPE" .
(See
.Sy MIME Enhancements
below.)
.It Ar mime-hook-TYPE-SUBTYPE
MIME-hook for MIME block of
.Ql "Content-Type: TYPE/SUBTYPE" .
(See
.Sy MIME Enhancements
below.)
.It Ev MBOX
The name of the
.Ar mbox
file.
It can be the name of a folder.
The default is
.Dq Li mbox
in the user's home directory.
.It Ar prompt
If defined, it specifies the prompt to use when in command mode.
Otherwise, the default
.Ql \*[Am]
is used.
The format syntax is the same as for
.Ar header-format .
.It Ar record
If defined, gives the pathname of the file used to record all outgoing
mail.
If not defined, then outgoing mail is not so saved.
.It Ar regex-search
If set, regular expression searches are used, instead of simple case
insensitive substring matches, when determining message lists by
searching sender names, subjects, or header fields (if
.Ar searchheaders
is defined); see the
.Sx Specifying message
section.
The value of the variable is a space or comma delimited list of
options.
Valid options are
.Ql icase
to do case insensitive searches,
.Ql extended
to use extended (rather than basic) regular expressions, and
.Ql nospec
to turn off all special character meanings and do literal string
searches.
Note that
.Ql extended
and
.Ql nospec
are not compatible (see
.Xr regcomp 3 ) .
.It Ar ReplyAsRecipient
This is used when replying to email (see the
.Ic reply
or
.Ic Reply
commands).
It is useful if you have multiple email addresses and wish to ensure
that replies respect them.
If set, grab the email address(es) from the
.Ql To
field of the message being replied to.
If there is only one such address, and if it does not match any
address in the value of
.Ar ReplyAsRecipient
(a comma or space delimited list of addresses, possibly empty), then
use this address in the
.Ql From
field of the reply.
This is accomplished by passing the address to
.Xr sendmail 1
with the
.Fl f
option.
Note: the sendmail options can be edited with the
.Ic \&~h
escape.
(See also the
.Ic smopts
command.)
.It Ar toplines
If defined, gives the number of lines of a message to be printed out
with the
.Ic top
command; normally, the first five lines are printed.
.El
.Ss MIME Enhancements
A MIME message is (recursively) divided into a series of MIME parts
that can be thought of as sub-messages, each with a header and body.
When MIME support is enabled (by setting
.Ar mime-decode-message ) ,
.Nm
splits a message into a series of its smallest MIME parts and
processes those parts as if they were messages themselves, passing the
header and body through a pipeline of the form:
.Pp
.Dl mail -\*[Gt] MIME-decoder -\*[Gt] MIME-hook -\*[Gt] pager -\*[Gt] screen
.Pp
The
.Em MIME-decoder
decodes
.Ql base64
or
.Ql quoted-printable
encoding and is enabled according to the
.Ql Content-Transfer-Encoding
of the part.
The
.Em MIME-hook
is an external program to further process the part (see below).
The
.Em pager
is the program that pages the message
(see
.Ev PAGER ) .
Any of these intermediate pipe stages may be missing and/or different
for the head and body of each MIME part.
Certain
.Ql Content-Types
may disable the entire pipeline (e.g.,
.Ql application/octet ) .
.Pp
The
.Em MIME-hook
stage is not present unless one of the following variables is set:
.Bd -literal -offset indent
mime-hook-TYPE-SUBTYPE    applies to the entire MIME part
mime-head-TYPE-SUBTYPE    applies to the header of the MIME part
mime-body-TYPE-SUBTYPE    applies to the body of the MIME part
.Ed
.Pp
where TYPE and SUBTYPE are the
.Ql Content-Type
type and subtype
(respectively) of the MIME part to which the hook applies.
If the
.Dq -SUBTYPE
is missing, any subtype is matched.
The value of these variables has the format:
.Bd -filled -offset indent
.Op Ar flags
.Ar command
.Ed
.Pp
where the
.Ar command
is expected to read from stdin and write to stdout, and the possible
flags are
.Bl -tag -width Ds -offset indent
.It !
Execute
.Ar command
in a sub-shell rather than doing an
.Xr exec 3
(see
.Va SHELL ) .
.It +
Use this hook when selecting the part to display in a
.Ql multipart/alternative
block.
Multipart blocks contain
.Dq alternative
versions with the same information, in increasing order of preference
(and decoding complexity).
The last one the mail agent understands is the one to be displayed.
This is typically used for sending a message in both
.Dq plain text
and
.Dq html ,
but more complex subtypes are also possible.
.It -
Do not decode before executing
.Ar command .
.El
.Pp
If your
.Ar command
begins with one of these flags, precede it with a space to signal the
end of the flags.
.Pp
WARNING: automatically running a program is a potential security risk
if that program has bugs, so be careful what you run.
.Pp
.Em Examples :
View all
.Ql "Content-Type: image/jpeg"
parts with
.Xr xv 1
(assuming it is installed):
.Pp
.Dl set mime-body-image-jpeg="/usr/pkg/bin/xv -"
.Pp
Decode all
.Ql "Content-Type: images/*"
blocks with
.Xr uudeview 1
(assuming it is installed), placing the results in
.Pa /tmp :
.Pp
.Dl set mime-hook-image="-/usr/pkg/bin/uudeview -p /tmp -i -a +o -q -"
.Pp
Read all
.Ql "Content-Type: text/html"
parts using
.Xr lynx 1
(assuming it is installed) and add this support to
.Ql multipart/alternative
blocks:
.Pp
.Bd -literal -offset indent
set mime-body-text-html="+/usr/pkg/bin/lynx -force_html -dump -stdin"
.Ed
.Sh ENVIRONMENT
.Nm
uses the
.Ev HOME ,
.Ev TMPDIR ,
and
.Ev USER
environment variables.
.Sh FILES
.Bl -tag -width /usr/share/misc/mail.*help -compact
.It Pa /var/mail/*
Post office.
.It ~/mbox
User's old mail.
.It ~/.mailrc
File giving initial mail commands.
This can be overridden by setting the
.Ev MAILRC
environment variable.
.It Pa /tmp/mail.R*
Temporary files.
.It Pa /usr/share/misc/mail.*help
Help files.
.It Pa /etc/mail.rc
System initialization file.
.El
.Sh SEE ALSO
.Xr fmt 1 ,
.Xr newaliases 1 ,
.Xr sendmail 1 ,
.Xr vacation 1 ,
.Xr aliases 5 ,
.Xr mailaddr 7
and
.Rs
.%T "The Mail Reference Manual"
.Re
.Sh HISTORY
A
.Nm
command
appeared in
.At v6 .
This man page is derived from
.%T "The Mail Reference Manual"
originally written by Kurt Shoens.
.Sh BUGS
There are some flags and commands that are not documented here.
Most are not useful to the general user.
.Pp
Usually,
.Nm
is just a link to
.Nm Mail ,
which can be confusing.
.Pp
The name of the
.Ic alternates
list is incorrect English (it should be
.Dq alternatives ) ,
but is retained for compatibility.
.Pp
There must be sufficient space on $TMPDIR for various temporary files.
.Pp
If an unrecoverable character set conversion error occurs (during
display), the message is truncated and a warning is printed.
This seems to be rare, but probably the remainder of the message
should be printed without conversion.
.Pp
The internal sh-like parser is not terribly sh-like.
.Pp
Selecting messages by their content (i.e., with
.Ql /body: )
is rather slow.