Last Update 1998-07-26
SENDMAIL(8) UNIX System Manager's Manual SENDMAIL(8)
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 for-
warding as necessary to deliver the message to the correct place.
Sendmail is not intended as a user interface routine; other programs pro-
vide user-friendly front ends; sendmail is used only to deliver pre-for-
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.
Normally the sender is not included in any alias expansions, e.g., if
`john' sends to `group', and `group' includes `john' in the expansion,
then the letter will not be delivered to `john'.
-Btype Set the body type to type. Current legal values 7BIT or
-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. This requires Berkeley IPC. Sendmail will
fork and run in background listening on socket 25 for incom-
ing 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 the persistent host status database.
-bi Initialize the alias database.
-bm Deliver mail in the usual way (default).
-bp Print a listing of the queue.
-bs Use the SMTP protocol as described in RFC821 on standard in-
put and output. This flag implies all the operations 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 configu-
-bv Verify names only - do not try to collect or deliver a mes-
sage. Verify mode is normally used for validating users or
-Cfile Use alternate configuration file. Sendmail refuses to run as
root if an alternate configuration file is specified.
-dX Set debugging value to X.
-Ffullname Set the full name of the sender.
-fname Sets the name of the ``from'' person (i.e., the sender of the
mail). -f can 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.
-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 mes-
sages. This should be set if you are reading data from a
-N dsn 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 message 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.
-ox value 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 Installation and Operation
Guide for details.
-pprotocol Set the name of the protocol used to receive the message.
This can be a simple protocol name such as ``UUCP'' or a pro-
tocol and hostname, such as ``UUCP:ucbvax''.
-q[time] Processed 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, `h'
being hours, `d' being days, and `w' being weeks. For exam-
ple, `-q1h30m' or `-q90m' would both set the timeout to one
hour thirty minutes. If time is specified, sendmail will run
in background. This option can be used safely with -bd.
-qIsubstr Limit processed jobs to those containing substr as a sub-
string of the queue id.
-qRsubstr Limit processed jobs to those containing substr as a sub-
string of one of the recipients.
-qSsubstr Limit processed jobs to those containing substr as a sub-
string of the sender.
-R return 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.
-rname 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.
-U Initial (user) submission. This should always be set when
called from a user agent such as Mail or exmh and never be
set when called by a network delivery agent such as rmail.
-V envid Set the original envelope id. This is propagated across SMTP
to servers that support DSNs and is returned in DSN-compliant
-v Go into verbose mode. Alias expansions will be announced,
-X logfile Log all traffic in and out of mailers in the indicated log
file. This should only be used as a last resort for debug-
ging mailer bugs. It will log a lot of data very quickly.
There are also a number of processing options that may be set. Normally
these will only be used by a system administrator. 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 queueing.
Checkpoint the queue file after every N successful deliveries
(default 10). This avoids excessive duplicate deliveries
when sending to long mailing lists interrupted by system
Set the delivery mode to x. Delivery modes are `i' for inter-
active (synchronous) delivery, `b' for background (asyn-
chronous) delivery, `q' for queue only - i.e., actual deliv-
ery is done the next time the queue is run, and `d' for de-
ferred - the same as `q' except that database lookups (no-
tably DNS and NIS lookups) are avoided.
Set error processing to mode x. Valid modes are `m' to mail
back the error message, `w' to ``write'' back the error mes-
sage (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 mes-
sage 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 directory.
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.
IgnoreDots Do not take dots on a line by themselves as a message termi-
Send error messages in MIME format. If not set, the DSN (De-
livery Status Notification) SMTP extension is disabled.
Set connection cache timeout.
Set connection cache size.
LogLevel=n The log level.
MeToo Send to ``me'' (the sender) also if I am in an alias expan-
Validate the right hand side of aliases during a newalias-
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 cases.
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 infor-
mation. You can consider this an adjunct to the aliasing
mechanism, except that the database is intended to be dis-
tributed; aliases are local to a particular host. This may
not be available if your sendmail does not have the USERDB
option compiled in.
Fork each job during queue runs. May be convenient on memo-
Strip incoming messages to seven bits.
Set the handling of eight bit input to seven bit destinations
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 message.
Sets how long a job must ferment in the queue between at-
tempts 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 mes-
sage 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:
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 recipients. For example, an alias such
would read /usr/local/lib/poets.list for the list of addresses making up
Sendmail returns an exit status describing what it did. The codes are
defined in <sysexits.h>:
EX_OK Successful completion on all addresses.
EX_NOUSER User name not recognized.
EX_UNAVAILABLE Catchall meaning necessary resources were not
EX_SYNTAX Syntax error in address.
EX_SOFTWARE Internal software error, including bad arguments.
EX_OSERR Temporary operating system error, such as ``cannot
EX_NOHOST Host name not recognized.
EX_TEMPFAIL Message could not be sent immediately, but was
If invoked as newaliases, sendmail will rebuild the alias database. If
invoked as mailq, sendmail will print the contents of the mail queue.
Except for the file /etc/sendmail.cf itself and the daemon process ID
file, the following pathnames are all specified in /etc/sendmail.cf.
Thus, these values are only approximations.
/etc/aliases raw data for alias names
/etc/aliases.db data base of alias names
/etc/sendmail.cf configuration file
/etc/sendmail.hf help file
/var/log/sendmail.st collected statistics
/var/spool/mqueue/* temp files
binmail(1), mail(1), rmail(1), syslog(3), aliases(5), mailaddr(7),
DARPA Internet Request For Comments RFC819, RFC821, RFC822.
Sendmail - An Internetwork Mail Router, No. 9, SMM.
Sendmail Installation and Operation Guide, No. 8, SMM.
The sendmail command appeared in 4.2BSD.
4th Berkeley Distribution April 2, 1998 6
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