sendmail - an electronic mail transport agent
sendmail [flags] [address ...]
Sendmail sends a message to one or more recipients, routing
the message over whatever networks are necessary. Sendmail
does internetwork forwarding as necessary to deliver the
message to the correct place.
Sendmail is not intended as a user interface routine; other
programs provide user-friendly front ends; sendmail is used
only to deliver pre-formatted messages.
With no flags, sendmail reads its standard input up to an
end-of-file or a line consisting only of a single dot and
sends a copy of the message found there to all of the
addresses listed. It determines the network(s) to use based
on the syntax and contents of the addresses.
Local addresses are looked up in a file and aliased
appropriately. Aliasing can be prevented by preceding the
address with a backslash. Beginning with 8.10, the sender
is included in any alias expansions, e.g., if `john' sends
to `group', and `group' includes `john' in the expansion,
then the letter will also be delivered to `john'.
-Ac Use submit.cf even if the operation mode does not indi-
cate an initial mail submission.
-Am Use sendmail.cf even if the operation mode indicates an
initial mail submission.
Set the body type to type. Current legal values are
7BIT or 8BITMIME.
-ba Go into ARPANET mode. All input lines must end with a
CR-LF, and all messages will be generated with a CR-LF
at the end. Also, the ``From:'' and ``Sender:'' fields
are examined for the name of the sender.
-bd Run as a daemon. Sendmail will fork and run in back-
ground listening on socket 25 for incoming SMTP
connections. This is normally run from /etc/rc.
-bD Same as -bd except runs in foreground.
-bh Print the persistent host status database.
-bH Purge expired entries from the persistent host status
-bi Initialize the alias database.
-bm Deliver mail in the usual way (default).
-bp Print a listing of the queue(s).
-bP Print number of entries in the queue(s); only available
with shared memory support.
-bs Use the SMTP protocol as described in RFC821 on stan-
dard input and output. This flag implies all the opera-
tions of the -ba flag that are compatible with SMTP.
-bt Run in address test mode. This mode reads addresses and
shows the steps in parsing; it is used for debugging
-bv Verify names only - do not try to collect or deliver a
message. Verify mode is normally used for validating
users or mailing lists.
Use alternate configuration file. Sendmail gives up
any enhanced (set-user-ID or set-group-ID) privileges
if an alternate configuration file is specified.
Send debugging output to the indicated log file instead
Set the debugging flag for category to level. Category
is either an integer or a name specifying the topic,
and level an integer specifying the level of debugging
output desired. Higher levels generally mean more out-
put. More than one flag can be specified by separating
them with commas. A list of numeric debugging
categories can be found in the TRACEFLAGS file in the
sendmail source distribution.
The option -d0.1 prints the version of sendmail and the
options it was compiled with.
Most other categories are only useful with, and docu-
mented in, sendmail's source code.
Set the full name of the sender.
Sets the name of the ``from'' person (i.e., the
envelope sender of the mail). This address may also be
used in the From: header if that header is missing dur-
ing initial submission. The envelope sender address is
used as the recipient for delivery status notifications
and may also appear in a Return-Path: header. -f
should only be used by ``trusted'' users (normally
root, daemon, and network) or if the person you are
trying to become is the same as the person you are.
Otherwise, an X-Authentication-Warning header will be
added to the message.
-G Relay (gateway) submission of a message, e.g., when
rmail calls sendmail .
-hN Set the hop count to N. The hop count is incremented
every time the mail is processed. When it reaches a
limit, the mail is returned with an error message, the
victim of an aliasing loop. If not specified,
``Received:'' lines in the message are counted.
-i Ignore dots alone on lines by themselves in incoming
messages. This should be set if you are reading data
from a file.
Set the identifier used in syslog messages to the sup-
Set delivery status notification conditions to dsn,
which can be `never' for no notifications or a comma
separated list of the values `failure' to be notified
if delivery failed, `delay' to be notified if delivery
is delayed, and `success' to be notified when the mes-
sage is successfully delivered.
-n Don't do aliasing.
Set option option to the specified value. This form
uses long names. See below for more details.
Set option x to the specified value. This form uses
single character names only. The short names are not
described in this manual page; see the Sendmail Instal-
lation and Operation Guide for details.
Set the name of the protocol used to receive the mes-
sage. This can be a simple protocol name such as
``UUCP'' or a protocol and hostname, such as
Process saved messages in the queue at given intervals.
If time is omitted, process the queue once. Time is
given as a tagged number, with `s' being seconds, `m'
being minutes (default), `h' being hours, `d' being
days, and `w' being weeks. For example, `-q1h30m' or
`-q90m' would both set the timeout to one hour thirty
minutes. By default, sendmail will run in the back-
ground. This option can be used safely with -bd.
Similar to -qtime, except that instead of periodically
forking a child to process the queue, sendmail forks a
single persistent child for each queue that alternates
between processing the queue and sleeping. The sleep
time is given as the argument; it defaults to 1 second.
The process will always sleep at least 5 seconds if the
queue was empty in the previous queue run.
-qf Process saved messages in the queue once and do not
fork(), but run in the foreground.
Process jobs in queue group called name only.
Limit processed jobs to those containing substr as a
substring of the queue id or not when ! is specified.
Limit processed jobs to quarantined jobs containing
substr as a substring of the quarantine reason or not
when ! is specified.
Limit processed jobs to those containing substr as a
substring of one of the recipients or not when ! is
Limit processed jobs to those containing substr as a
substring of the sender or not when ! is specified.
Quarantine a normal queue items with the given reason
or unquarantine quarantined queue items if no reason is
given. This should only be used with some sort of item
matching using as described above.
Set the amount of the message to be returned if the
message bounces. The return parameter can be `full' to
return the entire message or `hdrs' to return only the
headers. In the latter case also local bounces return
only the headers.
An alternate and obsolete form of the -f flag.
-t Read message for recipients. To:, Cc:, and Bcc: lines
will be scanned for recipient addresses. The Bcc: line
will be deleted before transmission.
Set the original envelope id. This is propagated across
SMTP to servers that support DSNs and is returned in
DSN-compliant error messages.
-v Go into verbose mode. Alias expansions will be
Log all traffic in and out of mailers in the indicated
log file. This should only be used as a last resort
for debugging mailer bugs. It will log a lot of data
-- Stop processing command flags and use the rest of the
arguments as addresses.
There are also a number of processing options that may be
set. Normally these will only be used by a system adminis-
trator. Options may be set either on the command line using
the -o flag (for short names), the -O flag (for long names),
or in the configuration file. This is a partial list limited
to those options that are likely to be useful on the command
line and only shows the long names; for a complete list (and
details), consult the Sendmail Installation and Operation
Guide. The options are:
Use alternate alias file.
On mailers that are considered ``expensive'' to connect
to, don't initiate immediate connection. This requires
Checkpoint the queue file after every N successful
deliveries (default 10). This avoids excessive dupli-
cate deliveries when sending to long mailing lists
interrupted by system crashes.
Set the delivery mode to x. Delivery modes are `i' for
interactive (synchronous) delivery, `b' for background
(asynchronous) delivery, `q' for queue only - i.e.,
actual delivery is done the next time the queue is run,
and `d' for deferred - the same as `q' except that
database lookups for maps which have set the -D option
(default for the host map) are avoided.
Set error processing to mode x. Valid modes are `m' to
mail back the error message, `w' to ``write'' back the
error message (or mail it back if the sender is not
logged in), `p' to print the errors on the terminal
(default), `q' to throw away error messages (only exit
status is returned), and `e' to do special processing
for the BerkNet. If the text of the message is not
mailed back by modes `m' or `w' and if the sender is
local to this machine, a copy of the message is
appended to the file dead.letter in the sender's home
Save UNIX-style From lines at the front of messages.
The maximum number of times a message is allowed to
``hop'' before we decide it is in a loop.
Do not take dots on a line by themselves as a message
Send error messages in MIME format. If not set, the DSN
(Delivery Status Notification) SMTP extension is dis-
Set connection cache timeout.
Set connection cache size.
The log level.
Don't send to ``me'' (the sender) if I am in an alias
Validate the right hand side of aliases during a
If set, this message may have old style headers. If not
set, this message is guaranteed to have new style
headers (i.e., commas instead of spaces between
addresses). If set, an adaptive algorithm is used that
will correctly determine the header format in most
Select the directory in which to queue messages.
Save statistics in the named file.
Set the timeout on undelivered messages in the queue to
the specified time. After delivery has failed (e.g.,
because of a host being down) for this amount of time,
failed messages will be returned to the sender. The
default is five days.
If set, a user database is consulted to get forwarding
information. You can consider this an adjunct to the
aliasing mechanism, except that the database is
intended to be distributed; aliases are local to a par-
ticular host. This may not be available if your send-
mail does not have the USERDB option compiled in.
Fork each job during queue runs. May be convenient on
Strip incoming messages to seven bits.
Set the handling of eight bit input to seven bit desti-
nations to mode: m (mimefy) will convert to seven-bit
MIME format, p (pass) will pass it as eight bits (but
violates protocols), and s (strict) will bounce the
Sets how long a job must ferment in the queue between
attempts to send it.
Sets the default character set used to label 8-bit data
that is not otherwise labelled.
If opening a connection fails, sleep for sleeptime
seconds and try again. Useful on dial-on-demand sites.
Set the behaviour when there are no recipient headers
(To:, Cc: or Bcc:) in the message to action: none
leaves the message unchanged, add-to adds a To: header
with the envelope recipients, add-apparently-to adds an
Apparently-To: header with the envelope recipients,
add-bcc adds an empty Bcc: header, and add-to-
undisclosed adds a header reading `To: undisclosed-
Sets the maximum number of children that an incoming
SMTP daemon will allow to spawn at any time to N.
Sets the maximum number of connections per second to
the SMTP port to N.
In aliases, the first character of a name may be a vertical
bar to cause interpretation of the rest of the name as a
command to pipe the mail to. It may be necessary to quote
the name to keep sendmail from suppressing the blanks from
between arguments. For example, a common alias is:
msgs: "|/usr/bin/msgs -s"
Aliases may also have the syntax ``:include:filename'' to
ask sendmail to read the named file for a list of reci-
pients. For example, an alias such as:
would read /usr/local/lib/poets.list for the list of
addresses making up the group.
Sendmail returns an exit status describing what it did. The
codes are defined in <sysexits.h>:
Successful completion on all addresses.
User name not recognized.
Catchall meaning necessary resources were not avail-
Syntax error in address.
Internal software error, including bad arguments.
Temporary operating system error, such as ``cannot
Host name not recognized.
Message could not be sent immediately, but was queued.
If invoked as newaliases, sendmail will rebuild the alias
database. If invoked as mailq, sendmail will print the con-
tents of the mail queue. If invoked as hoststat, sendmail
will print the persistent host status database. If invoked
as purgestat, sendmail will purge expired entries from the
persistent host status database. If invoked as smtpd, send-
mail will act as a daemon, as if the -bd option were speci-
sendmail often gets blamed for many problems that are actu-
ally the result of other problems, such as overly permissive
modes on directories. For this reason, sendmail checks the
modes on system directories and files to determine if they
can be trusted. Although these checks can be turned off and
your system security reduced by setting the DontBlameSend-
mail option, the permission problems should be fixed. For
more information, see:
Except for the file /etc/mail/sendmail.cf itself the
following pathnames are all specified in
/etc/mail/sendmail.cf. Thus, these values are only approxi-
raw data for alias names
data base of alias names
DARPA Internet Request For Comments RFC819, RFC821, RFC822.
Sendmail Installation and Operation Guide, No. 8, SMM.
The sendmail command appeared in 4.2BSD.
Man(1) output converted with