SENDMAIL(8) System Manager's Manual SENDMAIL(8)
sendmail - send mail over the internet
/usr/lib/sendmail [ -ba ] [ -bd ] [ -bi ] [ -bm ] [ -bp ] [ -bs ]
[ -bt ] [ -bv ] [ -bz ] [ -Cfile ] [ -dX ]
[ -Ffullname ] [ -fname ] [ -hN ] [ -n ] [ -ox value ]
[ -q[ time ] ] [ -rname ] [ -Rstring ] [ -t ] [ -v ] [ address ...
sendmail sends a message to one or more people, 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
provide user-friendly front ends; sendmail is used only to deliver pre-
With no flags, sendmail reads its standard input up to an EOF, or a
line with a single dot and sends a copy of the letter found there to
all of the addresses listed. It determines the network to use based on
the syntax and contents of the addresses.
Local addresses are looked up in the local aliases(5) file, or by using
the Network Information Service (NIS), and aliased appropriately. In
addition, if there is a .forward file in a recipient's home directory,
sendmail forwards a copy of each message to the list of recipients that
file contains. Aliasing can be prevented by preceding the address with
a backslash. Normally the sender is not included in alias expansions,
for example, if `john' sends to `group', and `group' includes `john' in
the expansion, then the letter will not be delivered to `john'.
sendmail will also route mail directly to other known hosts in a local
network. The list of hosts to which mail is directly sent is main-
tained in the file /usr/lib/mailhosts.
-ba Go into ARPANET mode. All input lines must end with a
LINEFEED, 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, waiting for incoming SMTP connections.
-bi Initialize the alias database.
-bm Deliver mail in the usual way (default).
-bp Print a summary of the mail queue.
-bs Use the SMTP protocol as described in RFC 821. 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
-bv Verify names only -- do not try to collect or deliver a
message. Verify mode is normally used for validating
users or mailing lists.
-bz Create the configuration freeze file.
-Cfile Use alternate configuration file.
-dX Set debugging value to X.
-Ffullname Set the full name of the sender.
-fname Sets the name of the ``from'' person (that is, the
sender of the mail). -f can only be used by ``trusted''
users (who are listed in the config file).
-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.
-Mid Attempt to deliver the queued message with message-id
-n Do not do aliasing.
-oxvalue Set option x to the specified value. Options are
-q[time] Processed saved messages in the queue at given inter-
vals. 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 example, -q1h30m or -q90m would both set the
timeout to one hour thirty minutes.
-rname An alternate and obsolete form of the -f flag.
-Rstring Go through the queue of pending mail and attempt to
deliver any message with a recipient containing the
specified string. This is useful for clearing out mail
directed to a machine which has been down for awhile.
-t Read message for recipients. ``To:'', ``Cc:'', and
``Bcc:'' lines will be scanned for people to send to.
The ``Bcc:'' line will be deleted before transmission.
Any addresses in the argument list will be suppressed.
-v Go into verbose mode. Alias expansions will be
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 or in the configu-
ration file. These are described in detail in the Installation and
Operation Guide. The options are:
Afile Use alternate alias file.
c On mailers that are considered ``expensive'' to connect to, do
not initiate immediate connection. This requires queueing.
dx Set the delivery mode to x. Delivery modes are i for interac-
tive (synchronous) delivery, b for background (asynchronous)
delivery, and q for queue only -- that is, actual delivery is
done the next time the queue is run.
D Run newaliases(8) to automatically rebuild the alias database,
ex 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 mes-
sages (only exit status is returned), and `e' to do special pro-
cessing 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.let-
ter in the sender's home directory.
Fmode The mode to use when creating temporary files.
f Save UNIX-system-style ``From'' lines at the front of messages.
gN The default group ID to use when calling mailers.
Hfile The SMTP help file.
i Do not take dots on a line by themselves as a message termina-
Ln The log level.
m Send to ``me'' (the sender) also if I am in an alias expansion.
o If set, this message may have old style headers. If not set,
this message is guaranteed to have new style headers (that is,
commas instead of spaces between addresses). If set, an adap-
tive algorithm is used that will correctly determine the header
format in most cases.
Select the directory in which to queue messages.
The timeout on reads; if none is set, sendmail will wait forever
for a mailer.
Sfile Save statistics in the named file.
s Always instantiate the queue file, even under circumstances
where it is not strictly necessary.
Ttime Set the timeout on messages in the queue to the specified time.
After sitting in the queue for this amount of time, they will be
returned to the sender. The default is three days.
Set the name of the time zone.
uN Set the default user id for mailers.
If the first character of the user name is a vertical bar, the rest of
the user name is used as the name of a program to pipe the mail to. It
may be necessary to quote the name of the user to keep sendmail from
suppressing the blanks from between arguments.
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 rebuilds the alias database. If
invoked as mailq, sendmail prints the contents of the mail queue.
Except for /etc/sendmail.cf, these pathnames are all specified in
/etc/sendmail.cf. Thus, these pathnames are only approximations.
/etc/aliases raw data for alias names
/etc/aliases.pag data base of alias names
/etc/sendmail.cf configuration file
/etc/sendmail.fc frozen configuration
/etc/sendmail.st collected statistics
/usr/bin/mail to deliver local mail
/usr/bin/uux to deliver uucp mail
/usr/lib/mailhosts list of hosts to which mail can be sent directly
/var/spool/mqueue/* temp files and queued mail
~/.forward list of recipients for forwarding messages
biff(1), bin-mail(1), mail(1), aliases(5) newaliases(8),
Su, Zaw-Sing, and Jon Postel, The Domain Naming Convention for Internet
User Applications, RFC 819, Network Information Center, SRI Interna-
tional, Menlo Park, Calif., August 1982.
Postel, Jon, Simple Mail Transfer Protocol, RFC 821, Network Informa-
tion Center, SRI International, Menlo Park, Calif., August 1982.
Crocker, Dave, Standard for the Format of ARPA-Internet Text Messages,
RFC 822, Network Information Center, SRI International, Menlo Park,
Calif., August 1982.
The Network Information Service (NIS) was formerly known as Sun Yellow
Pages (YP). The functionality of the two remains the same; only the
name has changed.
5 October 1990 SENDMAIL(8)