Computer Science
SENDMAIL(8) UNIX System Manager's Manual
SENDMAIL(8)
NAME
sendmail - an electronic mail transport agent
SYNOPSIS
sendmail [flags] [address ...]
newaliases
mailq [-v]
DESCRIPTION
Sendmail sends a message to one or more recipients, routing
the message
over whatever networks are necessary. Sendmail does inter-
network 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 de-
liver pre-for-
matted 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 appro-
priately.
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'.
Parameters
-Btype Set the body type to type. Current legal values
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. 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 oper-
ations of the
-ba flag that are compatible with SMTP.
-bt Run in address test mode. This mode reads ad-
dresses and
shows the steps in parsing; it is used for de-
bugging configu-
ration tables.
-bv Verify names only - do not try to collect or de-
liver a mes-
sage. Verify mode is normally used for validat-
ing users or
mailing lists.
-Cfile Use alternate configuration file. Sendmail re-
fuses to run as
root if an alternate configuration file is spec-
ified.
-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 incre-
mented every
time the mail is processed. When it reaches a
limit, the
mail is returned with an error message, the vic-
tim of an
aliasing loop. If not specified, ``Received:''
lines in the
message are counted.
-i Ignore dots alone on lines by themselves in in-
coming mes-
sages. This should be set if you are reading
data from a
file.
-N dsn Set delivery status notification conditions to
dsn, which can
be `never' for no notifications or a comma sepa-
rated 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 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 propagat-
ed 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 in-
dicated 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.
-- Stop processing command flags and use the rest
of the argu-
ments as addresses.
Options
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:
AliasFile=file
Use alternate alias file.
HoldExpensive
On mailers that are considered ``expensive'' to
connect to,
don't initiate immediate connection. This re-
quires queueing.
CheckpointInterval=N
Checkpoint the queue file after every N success-
ful 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 back-
ground (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.
ErrorMode=x
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 di-
rectory.
SaveFromLine
Save UNIX-style From lines at the front of mes-
sages.
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 termi-
nator.
SendMimeErrors
Send error messages in MIME format. If not set,
the DSN (De-
livery Status Notification) SMTP extension is
disabled.
ConnectionCacheTimeout=timeout
Set connection cache timeout.
ConnectionCacheSize=N
Set connection cache size.
LogLevel=n The log level.
MeToo Send to ``me'' (the sender) also if I am in an
alias expan-
sion.
CheckAliases
Validate the right hand side of aliases during a
newalias-
es(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
adaptive 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 for-
warding 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.
ForkEachJob
Fork each job during queue runs. May be conve-
nient on memo-
ry-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 at-
tempts 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 mes-
sage unchanged, add-to adds a To: header with
the envelope
recipients, add-apparently-to adds an Apparent-
ly-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 in-
coming SMTP
daemon will allow to spawn at any time to N.
ConnectionRateThrottle=N
Sets the maximum number of connections per sec-
ond 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 ad-
dresses making up
the group.
Sendmail returns an exit status describing what it did. The
codes are
defined in <sysexits.h>:
EX_OK Successful completion on all address-
es.
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.
FILES
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
SEE ALSO
binmail(1), mail(1), rmail(1), syslog(3), aliases(5),
mailaddr(7),
rc(8);
DARPA Internet Request For Comments RFC819, RFC821, RFC822.
Sendmail - An Internetwork Mail Router, No. 9, SMM.
Sendmail Installation and Operation Guide, No. 8, SMM.
HISTORY
The sendmail command appeared in 4.2BSD.
4th Berkeley Distribution August 2, 1998
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