SENDMAIL linux command manual
SENDMAIL(8) SENDMAIL(8)
NAME
sendmail - an electronic mail transport agent
SYNOPSIS
sendmail [flags] [address ...]
newaliases
mailq [-v]
hoststat
purgestat
smtpd
DESCRIPTION
Sendmail sends a message to one or more recipients, routing the mes-
sage 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 mes-
sage 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'.
Parameters
-Ac Use submit.cf even if the operation mode does not indicate an
initial mail submission.
-Am Use sendmail.cf even if the operation mode indicates an initial
mail submission.
-Btype 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 background lis-
tening 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 database.
-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 standard input
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 configuration
tables.
-bv Verify names only - do not try to collect or deliver a message.
Verify mode is normally used for validating users or mailing
lists.
-Cfile Use alternate configuration file. Sendmail gives up any
enhanced (set-user-ID or set-group-ID) privileges if an alter-
nate configuration file is specified.
-dcategory.level...
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 output. 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 documented in,
sendmail's source code.
-Ffullname
Set the full name of the sender.
-fname 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 during initial submission.
The envelope sender address is used as the recipient for deliv-
ery 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.
-L tag Set the identifier used in syslog messages to the supplied tag.
-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.
-O option=value
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 protocol
and hostname, such as ''UUCP:ucbvax''.
-q[time]
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 background. This option can be used safely with
-bd.
-qp[time]
Similar to -qtime, except that instead of periodically forking
a child to process the queue, sendmail forks a single persis-
tent child for each queue that alternates between processing
the queue and sleeping. The sleep time is given as the argu-
ment; 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.
-qG name
Process jobs in queue group called name only.
-q[!]Isubstr
Limit processed jobs to those containing substr as a substring
of the queue id or not when ! is specified.
-q[!]Rsubstr
Limit processed jobs to those containing substr as a substring
of one of the recipients or not when ! is specified.
-q[!]Ssubstr
Limit processed jobs to those containing substr as a substring
of the sender or not when ! is specified.
-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. In the
latter case also local bounces 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.
-V envid
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 announced, etc.
-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 debugging
mailer bugs. It will log a lot of data very quickly.
-- Stop processing command flags and use the rest of the arguments
as addresses.
Options
There are also a number of processing options that may be set. Nor-
mally 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:
AliasFile=file
Use alternate alias file.
HoldExpensive
On mailers that are considered ''expensive'' to connect to,
don't initiate immediate connection. This requires queueing.
CheckpointInterval=N
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 crashes.
DeliveryMode=x
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 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.
ErrorMode=x
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 directory.
SaveFromLine
Save UNIX-style From lines at the front of messages.
MaxHopCount=N
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 termina-
tor.
SendMimeErrors
Send error messages in MIME format. If not set, the DSN
(Delivery Status Notification) SMTP extension is disabled.
ConnectionCacheTimeout=timeout
Set connection cache timeout.
ConnectionCacheSize=N
Set connection cache size.
LogLevel=n
The log level.
MeToo=False
Don't send to ''me'' (the sender) if I am in an alias expan-
sion.
CheckAliases
Validate the right hand side of aliases during a newaliases(1)
command.
OldStyleHeaders
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 adap-
tive algorithm is used that will correctly determine the header
format in most cases.
QueueDirectory=queuedir
Select the directory in which to queue messages.
StatusFile=file
Save statistics in the named file.
Timeout.queuereturn=time
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.
UserDatabaseSpec=userdatabase
If set, a user database is consulted to get forwarding informa-
tion. You can consider this an adjunct to the aliasing mecha-
nism, except that the database is intended to be distributed;
aliases are local to a particular host. This may not be avail-
able if your sendmail does not have the USERDB option compiled
in.
ForkEachJob
Fork each job during queue runs. May be convenient on memory-
poor machines.
SevenBitInput
Strip incoming messages to seven bits.
EightBitMode=mode
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.
MinQueueAge=timeout
Sets how long a job must ferment in the queue between attempts
to send it.
DefaultCharSet=charset
Sets the default character set used to label 8-bit data that is
not otherwise labelled.
DialDelay=sleeptime
If opening a connection fails, sleep for sleeptime seconds and
try again. Useful on dial-on-demand sites.
NoRecipientAction=action
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 recipi-
ents, 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-
recipients:;'.
MaxDaemonChildren=N
Sets the maximum number of children that an incoming SMTP dae-
mon will allow to spawn at any time to N.
ConnectionRateThrottle=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 as:
poets: ":include:/usr/local/lib/poets.list"
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 :
EX_OK Successful completion on all addresses.
EX_NOUSER
User name not recognized.
EX_UNAVAILABLE
Catchall meaning necessary resources were not available.
EX_SYNTAX
Syntax error in address.
EX_SOFTWARE
Internal software error, including bad arguments.
EX_OSERR
Temporary operating system error, such as ''cannot fork''.
EX_NOHOST
Host name not recognized.
EX_TEMPFAIL
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 contents 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, sendmail will act as a daemon, as if the -bd option were
specified.
NOTES
sendmail often gets blamed for many problems that are actually the
result of other problems, such as overly permissive modes on directo-
ries. For this reason, sendmail checks the modes on system directo-
ries and files to determine if they can be trusted. Although these
checks can be turned off and your system security reduced by setting
the DontBlameSendmail option, the permission problems should be fixed.
For more information, see:
https://www.sendmail.org/tips/DontBlameSendmail.html
FILES
Except for the file /etc/mail/sendmail.cf itself the following path-
names are all specified in /etc/mail/sendmail.cf. Thus, these values
are only approximations.
/etc/aliases
raw data for alias names
/etc/mail/aliases.db
data base of alias names
/etc/mail/sendmail.cf
configuration file
/etc/mail/helpfile
help file
/var/log/mail/statistics
collected statistics
/var/spool/mqueue/*
temp files
SEE ALSO
mail(1), rmail(1), syslog(3), aliases(5), mailaddr(7),
DARPA Internet Request For Comments RFC819, RFC821, RFC822. Sendmail
Installation and Operation Guide, No. 8, SMM.
https://www.sendmail.org/
HISTORY
The sendmail command appeared in 4.2BSD.
$Date: 2003/12/01 17:02:00 $ SENDMAIL(8)