SENDMAIL(8) Maintenance Commands and Procedures SENDMAIL(8)

NAME

sendmail - send mail over the internet

SYNOPSIS

/usr/lib/sendmail [-Ac] [-Am] [-ba] [-bD] [-bd] [-bi] [-bl]
[-bm] [-bp] [-bP] [-bs] [-bt] [-bv] [-B type] [-C file]
[-D logfile] [-d X] [-F fullname] [-f name] [-G]
[-h N] [-L tag] [-M xvalue] [-N notifications] [-n]
[-Ooption =value] [-o xvalue] [-p protocol]
[-Q [reason]] [-q [time]] [-q Xstring] [-R ret]
[-r name] [-t] [-V envid] [-v] [-X logfile]
[address]...

DESCRIPTION

The sendmail utility sends a message to one or more people, 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 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 in a
name service as defined by the nsswitch.conf(5) file, 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. Refer to the NOTES
section for more information about .forward files. Aliasing can be
prevented by preceding the address with a backslash.


There are several conditions under which the expected behavior is for
the alias database to be either built or rebuilt. This cannot occur
under any circumstances unless root owns and has exclusive write
permission to the /etc/mail/aliases* files.


If a message is found to be undeliverable, it is returned to the
sender with diagnostics that indicate the location and nature of the
failure; or, the message is placed in a dead.letter file in the
sender's home directory.

Service Management

The sendmail service is managed by the service management facility,
smf(7), under the service identifiers:

svc:/network/smtp:sendmail
svc:/network/sendmail-client:default


Administrative actions on these services, such as enabling,
disabling, or requesting restart, can be performed using svcadm(8).
The services' status can be queried using the svcs(1) command.


These are separate services rather than instances of the same service
so that other services can properly express any dependencies. In
particular, here are some guidelines about which service/instance
should be depended on for which purposes:

o For a service that uses sendmail to send mail, an optional
dependency on the service svc:/network/sendmail-client
might be in order.

o For a service that needs to receive mail in general, but
does not depend on sendmail being the particular SMTP
receiver, a dependency on the service svc:/network/smtp
might be in order.

o For a service that needs to interact with sendmail in
particular, such as a Milter, a dependency on the instance
svc:/network/smtp:sendmail might be in order.


For the last two, note the difference, as the latter has the
":sendmail" instance specification, whereas the former does not, thus
representing the more general service.

Enabling Access to Remote Clients

On an unmodified system, access to sendmail by remote clients is
enabled and disabled through the service management facility (see
smf(7)). In particular, remote access is determined by the value of
the local_only SMF property:

svc:/network/smtp:sendmail/config/local_only = true


A setting of true, as above, disallows remote access; false allows
remote access. The default value is true.


The following example shows the sequence of SMF commands used to
enable sendmail to allow access to remote systems:

# svccfg -s svc:/network/smtp:sendmail setprop config/local_only = false
# svcadm refresh svc:/network/smtp:sendmail
# svcadm restart svc:/network/smtp:sendmail


See svcadm(8) and svccfg(8).


Note, however, on a system where any of the sendmail(5) files have
been customized, setting this property might not have the intended
effect. See sendmail(5) for details.

Automated Rebuilding of Configuration Files

See sendmail(5) for details on which service properties can be set to
automate (re)building of configuration files when the service is
started.

Restricting Host Access

sendmail uses TCP Wrappers to restrict access to hosts. It uses the
service name of sendmail for hosts_access(). For more information on
TCP Wrappers, see tcpd(8) and hosts_access(5).

Startup Options

The /etc/default/sendmail file stores startup options for sendmail so
that the options are not removed when a host is upgraded. See also
sendmail(5) for details on which service properties can be set to
automate (re)building of configuration files when the service is
started.


You can use the following variables in the /etc/default/sendmail
startup file:

CLIENTOPTIONS=string

Selects additional options to be used with the client daemon,
which looks in the client-only queue (/var/spool/clientmqueue)
and acts as a client queue runner. No syntax checking is done, so
be careful when making changes to this variable.


CLIENTQUEUEINTERVAL=#

Similar to the QUEUEINTERVAL option, CLIENTQUEUEINTERVAL sets the
time interval for mail queue runs. However, the
CLIENTQUEUEINTERVAL option controls the functions of the client
daemon, instead of the functions of the master daemon. Typically,
the master daemon is able to deliver all messages to the SMTP
port. However, if the message load is too high or the master
daemon is not running, then messages go into the client-only
queue, /var/spool/clientmqueue. The client daemon, which checks
in the client-only queue, then acts as a client queue processor.


ETRN_HOSTS=string

Enables an SMTP client and server to interact immediately without
waiting for the queue run intervals, which are periodic. The
server can immediately deliver the portion of its queue that goes
to the specified hosts. For more information, refer to the
etrn(8) man page.


MODE=-bd

Selects the mode to start sendmail with. Use the -bd option or
leave it undefined.


OPTIONS=string

Selects additional options to be used with the master daemon. No
syntax checking is done, so be careful when making changes to
this variable.


QUEUEINTERVAL=#

Sets the interval for mail queue runs on the master daemon. # can
be a positive integer that is followed by either s for seconds, m
for minutes, h for hours, d for days, or w for weeks. The syntax
is checked before sendmail is started. If the interval is
negative or if the entry does not end with an appropriate letter,
the interval is ignored and sendmail starts with a queue interval
of 15 minutes.


QUEUEOPTIONS=p

Enables one persistent queue runner that sleeps between queue run
intervals, instead of a new queue runner for each queue run
interval. You can set this option to p, which is the only setting
available. Otherwise, this option is not set.

Mail Filter API

sendmail supports a mail filter API called "milter". For more
information, see /usr/include/libmilter/README and
http://www.milter.org

OPTIONS

The following options are supported:

-Ac

Uses submit.cf even if the operation mode does not indicate an
initial mail submission.


-Am

Uses sendmail.cf even if the operation mode indicates an initial
mail submission.


-ba

Goes into ARPANET mode. All input lines must end with a RETURN-
LINEFEED, and all messages are generated with a RETURN-LINEFEED
at the end. Also, the From: and Sender: fields are examined for
the name of the sender.


-bd

Runs as a daemon in the background, waiting for incoming SMTP
connections.


-bD

Runs as a daemon in the foreground, waiting for incoming SMTP
connections.


-bi

Initializes the aliases(5) database. Root must own and have
exclusive write permission to the /etc/mail/aliases* files for
successful use of this option.


-bl

Runs as a daemon (like -bd) but accepts only loopback SMTP
connections.


-bm

Delivers mail in the usual way (default).


-bp

Prints a summary of the mail queues.


-bP

Prints the number of entries in the queues. This option is only
available with shared memory support.


-bs

Uses the SMTP protocol as described in RFC 2821. This flag
implies all the operations of the -ba flag that are compatible
with SMTP.


-bt

Runs in address test mode. This mode reads addresses and shows
the steps in parsing; it is used for debugging configuration
tables.


-bv

Verifies names only. Does not try to collect or deliver a
message. Verify mode is normally used for validating users or
mailing lists.


-B type

Indicates body type (7BIT or 8BITMIME).


-C file

Uses alternate configuration file.


-D logfile

Send debugging output to the indicated log file instead of
stdout.


-d X

Sets debugging value to X.


-f name

Sets the name of the "from" person (that is, the sender of the
mail).


-F fullname

Sets the full name of the sender.


-G

When accepting messages by way of the command line, indicates
that they are for relay (gateway) submission. When this flag is
set, sendmail might complain about syntactically invalid
messages, for example, unqualified host names, rather than fixing
them. sendmail does not do any canonicalization in this mode.


-h N

Sets 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.


-L tag

Sets the identifier used in syslog messages to the supplied tag.


-Mxvalue

Sets macro x to the specified value.


-n

Does not do aliasing.


-N notifications

Tags all addresses being sent as wanting the indicated
notifications, which consists of the word "NEVER" or a comma-
separated list of "SUCCESS", "FAILURE", and "DELAY" for
successful delivery, failure and a message that is stuck in a
queue somewhere. The default is "FAILURE,DELAY".


-oxvalue

Sets option x to the specified value. Processing Options are
described below.


-Ooption=value

Sets option to the specified value (for long from names).
Processing Options are described below.


-p protocol

Sets the sending protocol. The protocol field can be in form
protocol:host to set both the sending protocol and the sending
host. For example: -pUUCP:uunet sets the sending protocol to UUCP
and the sending host to uunet. Some existing programs use -oM to
set the r and s macros; this is equivalent to using -p.


-q[time]

Processes saved messages in the queue at given intervals. If time
is omitted, processes the queue once. time is given as a tagged
number, where s is seconds, m is minutes, h is hours, d is days,
and w is weeks. For example, -q1h30m or -q90m would both set the
timeout to one hour thirty minutes.

By default, sendmail runs in the background. This option can be
used safely with -bd.


-qp[time-]

Similar to -q[time], 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 (time) is specified as the argument;
it defaults to 1 second. The process always sleeps at least 5
seconds if the queue was empty in the previous queue run.


-qf

Processes saved messages in the queue once and does not fork(2),
but runs in the foreground.


-qG name

Processes jobs in queue group called name only.


-q[!]I substr

Limits processed jobs to those containing substr as a substring
of the queue ID or not when ! is specified.


-q[!]Q substr

Limits processed jobs to those quarantined jobs containing substr
as a substring of the quarantine reason or not when ! is
specified.


-q[!]R substr

Limits processed jobs to those containing substr as a substring
of one of the recipients or not when ! is specified.


-q[!]S substr

Limits processed jobs to those containing substr as a substring
of the sender or not when ! is specified.


-Q[reason]

Quarantines a normal queue item with the given reason or
unquarantines a quarantined queue item if no reason is given.
This should only be used with some sort of item matching as
described above.


-r name

An alternate and obsolete form of the -f flag.


-R ret

Identifies the information you want returned if the message
bounces. ret can be HDRS for headers only or FULL for headers
plus body.


-t

Reads message for recipients. To:,Cc:, and Bcc: lines are scanned
for people to send to. The Bcc: line is deleted before
transmission. Any addresses in the argument list is suppressed.
The NoRecipientAction Processing Option can be used to change the
behavior when no legal recipients are included in the message.


-v

Goes into verbose mode. Alias expansions are announced, and so
forth.


-V envid

The indicated envid is passed with the envelope of the message
and returned if the message bounces.


-X logfile

Logs all traffic in and out of sendmail in the indicated logfile
for debugging mailer problems. This produces a lot of data very
quickly and should be used sparingly.

Processing Options

There are a number of "random" options that can be set from a
configuration file. Options are represented by a single character or
by multiple character names. The syntax for the single character
names of is:

Oxvalue


This sets option x to be value. Depending on the option, value may be
a string, an integer, a boolean (with legal values t, T, f, or F; the
default is TRUE), or a time interval.


The multiple character or long names use this syntax:

O Longname=argument


This sets the option Longname to be argument. The long names are
beneficial because they are easier to interpret than the single
character names.


Not all processing options have single character names associated
with them. In the list below, the multiple character name is
presented first followed by the single character syntax enclosed in
parentheses.

AliasFile (Afile)

Specifies possible alias files.


AliasWait (a N)

If set, waits up to N minutes for an "@:@" entry to exist in the
aliases(5) database before starting up. If it does not appear in
N minutes, issues a warning. Defaults to 10 minutes.


AllowBogusHELO

Allows a HELO SMTP command that does not include a host name. By
default this option is disabled.


BadRcptThrottle=N

If set and more than the specified number of recipients in a
single SMTP envelope are rejected, sleeps for one second after
each rejected RCPT command.


BlankSub (Bc)

Sets the blank substitution character to c. Unquoted spaces in
addresses are replaced by this character. Defaults to SPACE (that
is, no change is made).


CACertFile

File containing one CA cert.


CACertPath

Path to directory with certs of CAs.


CheckAliases (n)

Validates the RHS of aliases when rebuilding the aliases(5)
database.


CheckpointInterval (CN)

Checkpoints the queue every N (default 10) addresses sent. If
your system crashes during delivery to a large list, this
prevents retransmission to any but the last N recipients.


ClassFactor (zfact)

The indicated factor fact is multiplied by the message class
(determined by the Precedence: field in the user header and the P
lines in the configuration file) and subtracted from the
priority. Thus, messages with a higher Priority: are favored.
Defaults to 1800.


ClientCertFile

File containing the cert of the client, that is, this cert is
used when sendmail acts as client.


ClientKeyFile

File containing the private key belonging to the client cert.


ClientPortOptions

Sets client SMTP options. The options are key=value pairs. Known
keys are:

Addr Address Mask

Address Mask defaults to INADDR_ANY. The address mask can be
a numeric address in dot notation or a network name.


Family

Address family (defaults to INET).


Listen

Size of listen queue (defaults to 10).


Port

Name/number of listening port (defaults to smtp).


RcvBufSize

The size of the TCP/IP receive buffer.


SndBufSize

The size of the TCP/IP send buffer.


Modifier

Options (flags) for the daemon. Can be:

h

Uses name of interface for HELO command.

If h is set, the name corresponding to the outgoing interface
address (whether chosen by means of the Connection parameter
or the default) is used for the HELO/EHLO command.


ColonOkInAddr

If set, colons are treated as a regular character in addresses.
If not set, they are treated as the introducer to the RFC 822
"group" syntax. This option is on for version 5 and lower
configuration files.


ConnectionCacheSize (kN)

The maximum number of open connections that are to be cached at a
time. The default is 1. This delays closing the current
connection until either this invocation of sendmail needs to
connect to another host or it terminates. Setting it to 0
defaults to the old behavior, that is, connections are closed
immediately.


ConnectionCacheTimeout (Ktimeout)

The maximum amount of time a cached connection is permitted to
idle without activity. If this time is exceeded, the connection
is immediately closed. This value should be small (on the order
of ten minutes). Before sendmail uses a cached connection, it
always sends a NOOP (no operation) command to check the
connection. If the NOOP command fails, it reopens the connection.
This keeps your end from failing if the other end times out. The
point of this option is to be a good network neighbor and avoid
using up excessive resources on the other end. The default is
five minutes.


ConnectionRateThrottle

The maximum number of connections permitted per second. After
this many connections are accepted, further connections are
delayed. If not set or <= 0, there is no limit.


ConnectionRateWindowSize

Define the length of the interval for which the number of
incoming connections is maintained. The default is 60 seconds.


ControlSocketName

Name of the control socket for daemon management. A running
sendmail daemon can be controlled through this Unix domain
socket. Available commands are: help, restart, shutdown, and
status. The status command returns the current number of daemon
children, the free disk space (in blocks) of the queue directory,
and the load average of the machine expressed as an integer. If
not set, no control socket is available. For the sake of
security, this Unix domain socket must be in a directory which is
accessible only by root; /var/spool/mqueue/.smcontrol is
recommended for the socket name.


CRLFile

File containing certificate revocation status, useful for X.509v3
authentication.


DaemonPortOptions (Ooptions)

Sets server SMTP options. The options are key=value pairs. Known
keys are:

Name

User-definable name for the daemon (defaults to "Daemon#").
Used for error messages and logging.


Addr

Address mask (defaults INADDR_ANY).

The address mask may be a numeric address in dot notation or
a network name.


Family

Address family (defaults to INET).


InputMailFilters

List of input mail filters for the daemon.


Listen

Size of listen queue (defaults to 10).


Modifier

Options (flags) for the daemon; can be a sequence (without
any delimiters) of:

a

Requires authentication.


b

Binds to interface through which mail has been received.


c

Performs hostname canonification (.cf).


f

Requires fully qualified hostname (.cf).


h

Uses name of interface for HELO command.


u

Allows unqualified addresses (.cf).


C

Does not perform hostname canonification.


E

Disallows ETRN (see RFC 2476).


Name

User-definable name for the daemon (defaults to Daemon#).
Used for error messages and logging.


Port

Name/number of listening port (defaults to smtp).


ReceiveSize

The size of the TCP/IP receive buffer.


SendSize

The size of the TCP/IP send buffer.


children

Maximum number of children per daemon. See MaxDaemonChildren.


DeliveryMode

Delivery mode per daemon. See DeliveryMode.


refuseLA

RefuseLA per daemon.


delayLA

DelayLA per daemon.


queueLA

QueueLA per daemon.

sendmail listens on a new socket for each occurrence of the
DaemonPortOptions option in a configuration file.


DataFileBufferSize

Sets the threshold, in bytes, before a memory-bases queue data
file becomes disk-based. The default is 4096 bytes.


DeadLetterDrop

Defines the location of the system-wide dead.letter file,
formerly hard-coded to /var/tmp/dead.letter. If this option is
not set (the default), sendmail does not attempt to save to a
system-wide dead.letter file in the event it cannot bounce the
mail to the user or postmaster. Instead, it renames the qf file
as it has in the past when the dead.letter file could not be
opened.


DefaultCharSet

Sets the default character set to use when converting unlabeled 8
bit input to MIME.


DefaultUser (ggid) or (uuid)

Sets the default group ID for mailers to run in to gid or set the
default userid for mailers to uid. Defaults to 1. The value can
also be given as a symbolic group or user name.


DelayLA=LA

When the system load average exceeds LA, sendmail sleeps for one
second on most SMTP commands and before accepting connections.


DeliverByMin=time

Sets minimum time for Deliver By SMTP Service Extension (RFC
2852). If 0, no time is listed, if less than 0, the extension is
not offered, if greater than 0, it is listed as minimum time for
the EHLO keyword DELIVERBY.


DeliveryMode (dx)

Delivers in mode x. Legal modes are:

i

Delivers interactively (synchronously).


b

Delivers in background (asynchronously).


d

Deferred mode. Database lookups are deferred until the actual
queue run.


q

Just queues the message (delivers during queue run).

Defaults to b if no option is specified, i if it is specified but
given no argument (that is, Od is equivalent to Odi).


DHParameters

File containing the DH parameters.


DialDelay

If a connection fails, waits this many seconds and tries again.
Zero means "do not retry".


DontBlameSendmail

If set, overrides the file safety checks. This compromises system
security and should not be used. See
http://www.sendmail.org/tips/DontBlameSendmail.html for more
information.


DontExpandCnames

If set, $[ ... $] lookups that do DNS-based lookups do not expand
CNAME records.


DontInitGroups

If set, the initgroups(3C) routine is never invoked. If you set
this, agents run on behalf of users only have their primary
(/etc/passwd) group permissions.


DontProbeInterfaces

If set, sendmail does not insert the names and addresses of any
local interfaces into the $=w class. If set, you must also
include support for these addresses, otherwise mail to addresses
in this list bounces with a configuration error.


DontPruneRoutes (R)

If set, does not prune route-addr syntax addresses to the minimum
possible.


DoubleBounceAddress

If an error occurs when sending an error message, sends that
"double bounce" error message to this address.


EightBitMode (8)

Uses 8-bit data handling. This option requires one of the
following keys. The key can selected by using just the first
character, but using the full word is better for clarity.

mimify

Does any necessary conversion of 8BITMIME to 7-bit.


pass

Passes unlabeled 8-bit input through as is.


strict

Rejects unlabeled 8-bit input.


ErrorHeader (Efile/message)

Appends error messages with the indicated message. If it begins
with a slash, it is assumed to be the pathname of a file
containing a message (this is the recommended setting).
Otherwise, it is a literal message. The error file might contain
the name, email address, and/or phone number of a local
postmaster who could provide assistance to end users. If the
option is missing or NULL, or if it names a file which does not
exist or which is not readable, no message is printed.


ErrorMode (ex)

Disposes of errors using mode x. The values for x are:

e

Mails back errors and gives 0 exit status always.


m

Mails back errors.


p

Prints error messages (default).


q

No messages, just gives exit status.


w

Writes back errors (mail if user not logged in).


FallbackMXhost (Vfallbackhost)

If specified, the fallbackhost acts like a very low priority MX
on every host. This is intended to be used by sites with poor
network connectivity.


FallBackSmartHost

If specified, the fallBackSmartHost is used in a last-ditch
effort for each host. This is intended to be used by sites with
"fake internal DNS". That is, a company whose DNS accurately
reflects the world inside that company's domain but not outside.


FastSplit

If set to a value greater than zero (the default is one), it
suppresses the MX lookups on addresses when they are initially
sorted, that is, for the first delivery attempt. This usually
results in faster envelope splitting unless the MX records are
readily available in a local DNS cache. To enforce initial
sorting based on MX records set FastSplit to zero. If the mail is
submitted directly from the command line, then the value also
limits the number of processes to deliver the envelopes; if more
envelopes are created they are only queued up and must be taken
care of by a queue run. Since the default submission method is by
way of SMTP (either from a MUA or by way of the Message
Submission Program [MSP]), the value of FastSplit is seldom used
to limit the number of processes to deliver the envelopes.


ForkEachJob (Y)

If set, delivers each job that is run from the queue in a
separate process. Use this option if you are short of memory,
since the default tends to consume considerable amounts of memory
while the queue is being processed.


ForwardPath (Jpath)

Sets the path for searching for users' .forward files. The
default is $z/.forward. Some sites that use the automounter may
prefer to change this to /var/forward/$u to search a file with
the same name as the user in a system directory. It can also be
set to a sequence of paths separated by colons; sendmail stops at
the first file it can successfully and safely open. For example,
/var/forward/$u:$z/.forward searches first in /var/forward/
username and then in ~username/.forward (but only if the first
file does not exist). Refer to the NOTES section for more
information.


HeloName=name

Sets the name to be used for HELO/EHLO (instead of $j).


HelpFile (Hfile)

Specifies the help file for SMTP.


HoldExpensive (c)

If an outgoing mailer is marked as being expensive, does not
connect immediately.


HostsFile

Sets the file to use when doing "file" type access of host names.


HostStatusDirectory

If set, host status is kept on disk between sendmail runs in the
named directory tree. If a full path is not used, then the path
is interpreted relative to the queue directory.


IgnoreDots (i)

Ignores dots in incoming messages. This is always disabled (that
is, dots are always accepted) when reading SMTP mail.


LogLevel (Ln)

Sets the default log level to n. Defaults to 9.


(Mxvalue)

Sets the macro x to value. This is intended only for use from the
command line.


MailboxDatabase

Type of lookup to find information about local mail boxes,
defaults to pw which uses getpwnam(3C). Other types can be
introduced by adding them to the source code, see libsm/mbdb.c
for details.


MatchGECOS (G)

Tries to match recipient names using the GECOS field. This allows
for mail to be delivered using names defined in the GECOS field
in /etc/passwd as well as the login name.


MaxDaemonChildren

The maximum number of children the daemon permits. After this
number, connections are rejected. If not set or <=0, there is no
limit.


MaxHopCount (hN)

The maximum hop count. Messages that have been processed more
than N times are assumed to be in a loop and are rejected.
Defaults to 25.


MaxMessageSize

The maximum size of messages that are accepted (in bytes).


MaxMimeHeaderLength=M[/N]

Sets the maximum length of certain MIME header field values to M
characters. For some of these headers which take parameters, the
maximum length of each parameter is set to N if specified. If /N
is not specified, one half of M is used. By default, these values
are 0, meaning no checks are done.


MaxNOOPCommands=N

Overrides the default of 20 for the number of useless commands.


MaxQueueChildren=N

When set, this limits the number of concurrent queue runner
processes to N. This helps to control the amount of system
resources used when processing the queue. When there are multiple
queue groups defined and the total number of queue runners for
these queue groups would exceed MaxQueueChildren then the queue
groups are not all run concurrently. That is, some portion of the
queue groups run concurrently such that MaxQueueChildren is not
be exceeded, while the remaining queue groups are run later (in
round robin order). See MaxRunnersPerQueue.


MaxQueueRunSize

If set, limits the maximum size of any given queue run to this
number of entries. This stops reading the queue directory after
this number of entries is reached; job priority is not used. If
not set, there is no limit.


MaxRunnersPerQueue=N

This sets the default maximum number of queue runners for queue
groups. Up to N queue runners work in parallel on a queue group's
messages. This is useful where the processing of a message in the
queue might delay the processing of subsequent messages. Such a
delay can be the result of non-erroneous situations such as a low
bandwidth connection. The can be overridden on a per queue group
basis by setting the Runners option. The default is 1 when not
set.


MeToo (M)

Sends to me too, even if I am in an alias expansion.


MaxRecipientsPerMessage

If set, allows no more than the specified number of recipients in
an SMTP envelope. Further recipients receive a 452 error code and
are deferred for the next delivery attempt.


MinFreeBlocks (bN/M)

Insists on at least N blocks free on the file system that holds
the queue files before accepting email by way of SMTP. If there
is insufficient space, sendmail gives a 452 response to the MAIL
command. This invites the sender to try again later. The optional
M is a maximum message size advertised in the ESMTP EHLO
response. It is currently otherwise unused.


MinQueueAge

Specifies the amount of time a job must sit in the queue between
queue runs. This allows you to set the queue run interval low
for better responsiveness without trying all jobs in each run.
The default value is 0.


MustQuoteChars

Specifies the characters to be quoted in a full name phrase.
&,;:\()[] are quoted automatically.


NiceQueueRun

Specifies the priority of queue runners. See nice(1).


NoRecipientAction

Sets action if there are no legal recipient files in the message.
The legal values are:

add-apparently-to

Adds an Apparently-to: header with all the known recipients
(which may expose blind recipients).


add-bcc

Adds an empty Bcc: header.


add-to

Adds a To: header with all the known recipients (which may
expose blind recipients).


add-to-undisclosed

Adds a To: undisclosed-recipients: header.


none

Does nothing, that is, leaves the message as it is.


OldStyleHeaders (o)

Assumes that the headers may be in old format, that is, spaces
delimit names. This actually turns on an adaptive algorithm: if
any recipient address contains a comma, parenthesis, or angle
bracket, it is assumed that commas already exist. If this flag is
not on, only commas delimit names. Headers are always output with
commas between the names.


OperatorChars or $o

Defines the list of characters that can be used to separate the
components of an address into tokens.


PidFile

Specifies the filename of the pid file. The default is
/var/run/sendmail.pid. The filename is macro-expanded before it
is opened, and unlinked when sendmail exits.


PostmasterCopy (Ppostmaster)

If set, copies of error messages are sent to the named
postmaster. Only the header of the failed message is sent. Since
most errors are user problems, this is probably not a good idea
on large sites, and arguably contains all sorts of privacy
violations, but it seems to be popular with certain operating
systems vendors.


PrivacyOptions (popt,opt,...)

Sets privacy options. Privacy is really a misnomer; many of these
options are just a way of insisting on stricter adherence to the
SMTP protocol.

The goaway pseudo-flag sets all flags except noreceipts,
restrictmailq, restrictqrun, restrictexpand, noetrn, and
nobodyreturn. If mailq is restricted, only people in the same
group as the queue directory can print the queue. If queue runs
are restricted, only root and the owner of the queue directory
can run the queue. The restrict-expand pseudo-flag instructs
sendmail to drop privileges when the -bv option is given by users
who are neither root nor the TrustedUser so users cannot read
private aliases, forwards, or :include: files. It adds the
NonRootSafeAddr to the "DontBlame-Sendmail" option to prevent
misleading unsafe address warnings. It also overrides the -v
(verbose) command line option to prevent information leakage.
Authentication Warnings add warnings about various conditions
that may indicate attempts to fool the mail system, such as using
an non-standard queue directory.

The options can be selected from:

authwarnings

Puts X-Authentication-Warning: headers in messages.


goaway

Disallows essentially all SMTP status queries.


needexpnhelo

Insists on HELO or EHLO command before EXPN.


needmailhelo

Insists on HELO or EHLO command before MAIL.


needvrfyhelo

Insists on HELO or EHLO command before VRFY.


noactualrecipient

Do not put an X-Actual-Recipient line in a DNS that reveals
the actual account to which an address is mapped.


noetrn

Disallows ETRN entirely.


noexpn

Disallows EXPN entirely.


noreceipts

Prevents return receipts.


nobodyreturn

Does not return the body of a message with DSNs.


novrfy

Disallows VRFY entirely.


public

Allows open access.


restrictexpand

Restricts -bv and -v command line flags.


restrictmailq

Restricts mailq command.


restrictqrun

Restricts -q command line flag.


ProcessTitlePrefix string

Prefixes the process title shown on "/usr/ucb/ps auxww" listings
with string. The string is macro processed.


QueueDirectory (Qdir)

Uses the named dir as the queue directory.


QueueFactor (qfactor)

Uses factor as the multiplier in the map function to decide when
to just queue up jobs rather than run them. This value is divided
by the difference between the current load average and the load
average limit (x flag) to determine the maximum message priority
to be sent. Defaults to 600000.


QueueFileMode=mode

Defaults permissions for queue files (octal). If not set,
sendmail uses 0600 unless its real and effective uid are
different in which case it uses 0644.


QueueLA (xLA)

When the system load average exceeds LA, just queues messages
(that is, does not try to send them). Defaults to eight times the
number of processors online when sendmail starts.


QueueSortOrder=algorithm

Sets the algorithm used for sorting the queue. Only the first
character of the value is used. Legal values are host (to order
by the name of the first host name of the first recipient),
filename (to order by the name of the queue file name), time (to
order by the submission/creation time), random (to order
randomly), modification (to order by the modification time of the
qf file (older entries first)), none (to not order), and priority
(to order by message priority). Host ordering makes better use of
the connection cache, but may tend to process low priority
messages that go to a single host over high priority messages
that go to several hosts; it probably shouldn't be used on slow
network links. Filename and modification time ordering saves the
overhead of reading all of the queued items before starting the
queue run. Creation (submission) time ordering is almost always a
bad idea, since it allows large, bulk mail to go out before
smaller, personal mail, but may have applicability on some hosts
with very fast connections. Random is useful if several queue
runners are started by hand which try to drain the same queue
since odds are they are working on different parts of the queue
at the same time. Priority ordering is the default.


QueueTimeout (Trtime/wtime)

Sets the queue timeout to rtime. After this interval, messages
that have not been successfully sent are returned to the sender.
Defaults to five days (5d). The optional wtime is the time after
which a warning message is sent. If it is missing or 0, then no
warning messages are sent.


RandFile

File containing random data (use prefix file:) or the name of the
UNIX socket if EGD is used (use prefix egd:). Note that Solaris
supports random(4D), so this does not need to be specified.


RecipientFactor (yfact)

The indicated factor fact is added to the priority (thus lowering
the priority of the job) for each recipient, that is, this value
penalizes jobs with large numbers of recipients. Defaults to
30000.


RefuseLA (XLA)

When the system load average exceeds LA, refuses incoming SMTP
connections. Defaults to 12 times the number of processors online
when sendmail starts.


RejectLogInterval

Log interval when refusing connections for this long (default:
3h).


ResolverOptions (I)

Tunes DNS lookups.


RetryFactor (Zfact)

The indicated factor fact is added to the priority every time a
job is processed. Thus, each time a job is processed, its
priority is decreased by the indicated value. In most
environments this should be positive, since hosts that are down
are all too often down for a long time. Defaults to 90000.


RrtImpliesDsn

If this option is set, a Return-Receipt-To: header causes the
request of a DSN, which is sent to the envelope sender as
required by RFC 1891, not to the address given in the header.


RunAsUser

If set, becomes this user when reading and delivering mail.
Intended for use of firewalls where users do not have accounts.


SafeFileEnvironment

If set, sendmail does a chroot into this directory before writing
files.


SaveFromLine (f)

Saves Unix-style From lines at the front of headers. Normally
they are assumed redundant and discarded.


SendMimeErrors (j)

If set, sends error messages in MIME format (see RFC 2045 and RFC
1344 for details). If disabled, sendmail does not return the DSN
keyword in response to an EHLO and does not do Delivery Status
Notification processing as described in RFC 1891.


ServerCertFile

File containing the cert of the server, that is, this cert is
used when sendmail acts as server.


ServerKeyFile

File containing the private key belonging to the server cert.


ServiceSwitchFile

Defines the path to the service-switch file. Since the service-
switch file is defined in the Solaris operating environment this
option is ignored.


SevenBitInput (7)

Strips input to seven bits for compatibility with old systems.
This should not be necessary.


SharedMemoryKey

Specifies key to use for shared memory segment. If not set (or
0), shared memory is not be used. If this option is set, sendmail
can share some data between different instances. For example, the
number of entries in a queue directory or the available space in
a file system. This allows for more efficient program execution,
since only one process needs to update the data instead of each
individual process gathering the data each time it is required.


SharedMemoryKeyFile=file

If SharedMemoryKeyFile is set to -1, the automatically selected
shared memory key will be stored in the specified file.


SingleLineFromHeader

If set, From: lines that have embedded newlines are unwrapped
onto one line.


SingleThreadDelivery

If this option and the HostStatusDirectory option are both set,
uses single thread deliveries to other hosts.


SmtpGreetingMessage or $e

Specifies the initial SMTP greeting message.


SoftBounce

If set, issue temporary errors (4xy) instead of permanent errors
(5xy). This can be useful during testing of a new configuration
to avoid erroneous bouncing of mail.


StatusFile (Sfile)

Logs statistics in the named file. By default, this is
/etc/mail/sendmail.st. As root, you must touch(1) this file to
enable mailstats(1).


SuperSafe (s)

This option can be set to True, False, Interactive, or
PostMilter. If set to True, sendmail is set to super-safe when
running things, that is, always instantiate the queue file, even
if you are going to attempt immediate delivery. sendmail always
instantiates the queue file before returning control to the
client under any circumstances. This should really always be set
to True. The Interactive value has been introduced in 8.12 and
can be used together with DeliveryMode=i. It skips some
synchronization calls which are effectively doubled in the code
execution path for this mode. If set to PostMilter, sendmail
defers synchronizing the queue file until any milters have
signaled acceptance of the message. PostMilter is useful only
when sendmail is running as an SMTP server; in all other
situations it acts the same as True.


TempFileMode (Fmode)

Specifies the file mode for queue files.


Timeout (rtimeouts)

Timeout reads after time interval. The timeouts argument is a
list of keyword=value pairs. All but command apply to client
SMTP. For backward compatibility, a timeout with no keyword=
part is set all of the longer values. The recognized timeouts and
their default values, and their minimum values specified in RFC
1123 section 5.3.2 are:

aconnect

all connections for a single delivery attempt [0,
unspecified]


command

command read [1h, 5m]


connect

initial connect [0, unspecified]


control

complete control socket transaction [2m, none]


datablock

data block read [1h, 3m]


datafinal

reply to final . in data [1h, 10m]


datainit

reply to DATA command [5m, 2m]


fileopen

file open [60sec, none]


helo

reply to HELO or EHLO command [5m, none]


hoststatus

host retry [30m, unspecified]


iconnect

first attempt to connect to a host [0, unspecified]


ident

IDENT protocol timeout [5s, none]


initial

wait for initial greeting message [5m, 5m]


lhlo

wait for reply to an LMTP LHLO command [2m, unspecified]


mail

reply to MAIL command [10m, 5m]


misc

reply to NOOP and VERB commands [2m, none]


queuereturn

undeliverable message returned [5d]


queuewarn

deferred warning [4h]


quit

reply to QUIT command [2m, none]


rcpt

reply to RCPT command [1h, 5m]


resolver.retrans

Resolver's retransmission time interval (in seconds)
[varies]. Sets both Timeout.resolver.retrans.first and
Timeout.resolver.retrans.normal.


resolver.retrans.first

Resolver's retransmission time interval (in seconds) for the
first attempt to deliver a message [varies].


resolver.retrans.normal

Resolver's retransmission time interval (in seconds) for all
look-ups except the first delivery attempt [varies].


resolver.retry

Number of times to retransmit a resolver query [varies]. Sets
both Timeout.resolver.retry.first and
Timeout.resolver.retry.normal.


resolver.retry.first

Number of times to retransmit a resolver query for the first
attempt to deliver a message [varies].


resolver.retry.normal

Number of times to retransmit a resolver query for all look-
ups except the first delivery attempt [varies].


rset

reply to RSET command [5m, none]


starttls

response to an SMTP STARTTLS command [1h]


TimeZoneSpec (ttzinfo)

Sets the local time zone info to tzinfo, for example, "PST8PDT".
Actually, if this is not set, the TZ environment variable is
cleared (so the system default is used); if set but null, the
user's TZ variable is used, and if set and non-null, the TZ
variable is set to this value.


TLSSrvOptions

If this option is 'V', then no client verification is
performed,that is, the server does not ask for a certificate.


TrustedUser

The user parameter can be a user name (looked up in the passwd
map) or a numeric user id. Trusted user for file ownership and
starting the daemon. If set, generated alias databases and the
control socket (if configured) are automatically owned by this
user.


TryNullMXList (w)

If you are the "best" (that is, lowest preference) MX for a given
host, you should normally detect this situation and treat that
condition specially, by forwarding the mail to a UUCP feed,
treating it as local, or whatever. However, in some cases (such
as Internet firewalls) you may want to try to connect directly to
that host as though it had no MX records at all. Setting this
option causes sendmail to try this. The downside is that errors
in your configuration are likely to be diagnosed as "host
unknown" or "message timed out" instead of something more
meaningful. This option is deprecated.


UnixFromLine or $l

The "From " line used when sending to files or programs.


UnsafeGroupWrites

If set, group-writable :include: and .forward files are
considered "unsafe", that is, programs and files cannot be
directly referenced from such files.


UseErrorsTo (l)

If there is an Errors-To: header, sends error messages to the
addresses listed there. They normally go to the envelope sender.
Use of this option causes sendmail to violate RFC 1123. This
option is not recommended and deprecated.


UseMSP

Uses as mail submission program, that is, allows group writable
queue files if the group is the same as that of a set-group-id
sendmail binary.


UserDatabaseSpec (U)

Defines the name and location of the file containing User
Database information.


Verbose (v)

Runs in verbose mode. If this is set, sendmail adjusts the
HoldExpensive and DeliveryMode options so that all mail is
delivered completely in a single job so that you can see the
entire delivery process. The Verbose option should never be set
in the configuration file; it is intended for command line use
only.


XscriptFileBufferSize

Sets the threshold, in bytes, before a memory-bases queue
transcript file becomes disk-based. The default is 4096 bytes.


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.


If invoked as newaliases, sendmail rebuilds the alias database, so
long as the /etc/mail/aliases* files are owned by root and root has
exclusive write permission. If invoked as mailq, sendmail prints the
contents of the mail queue.

OPERANDS

address

address of an intended recipient of the message being sent.

USAGE

See largefile(7) for the description of the behavior of sendmail when
encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).

EXIT STATUS

sendmail returns an exit status describing what it did. The codes are
defined in /usr/include/sysexits.h.

EX_OK

Successful completion on all addresses.


EX_NOUSER

User name not recognized.


EX_UNAVAILABLE

Catchall. 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.

ENVIRONMENT VARIABLES

No environment variables are used. However, sendmail's start-up
script, invoked by svcadm(8), reads /etc/default/sendmail. In this
file, if the variable ETRN_HOSTS is set, the start-up script parses
this variable and invokes etrn(8) appropriately. ETRN_HOSTS should be
of the form:

"s1:c1.1,c1.2 s2:c2.1 s3:c3.1,c3.2,c3.3"


That is, white-space separated groups of server:client where client
can be one or more comma-separated names. The :client part is
optional. server is the name of the server to prod; a mail queue run
is requested for each client name. This is comparable to running:

/usr/lib/sendmail -qR client


on the host server.

FILES

dead.letter

Unmailable text


/etc/default/sendmail

Contains default settings. You can override some of the settings
by command line options.


/etc/mail/aliases

Mail aliases file (ASCII)


/etc/mail/aliases.db

Database of mail aliases (binary)


/etc/mail/aliases.dir

Database of mail aliases (binary)


/etc/mail/aliases.pag

Database of mail aliases (binary)


/etc/mail/sendmail.cf

Defines environment for sendmail


/etc/mail/submit.cf

Defines environment for MSP


/etc/mail/trusted-users

Lists users that are "trusted", that is, able to set their
envelope from address using -f without generating a warning
message. Note that this file is consulted by the default
sendmail.cf, but not by the default submit.cf, in which the line
referring to /etc/mail/trusted-users is commented out. See
sendmail(5) for instructions on making changes to submit.cf and
sendmail.cf.


/var/spool/clientmqueue/*

Temporary files and queued mail


/var/spool/mqueue/*

Temporary files and queued mail


~/.forward

List of recipients for forwarding messages


/usr/include/libmilter/README

Describes the steps needed to compile and run a filter

SEE ALSO

mail(1), mailq(1), mailx(1), nice(1), svcs(1), biff(1B), fork(2),
getpwnam(3C), getusershell(3C), resolver(3RESOLV), random(4D),
aliases(5), hosts(5), hosts_access(5), sendmail(5), shells(5),
attributes(7), largefile(7), smf(7), check-hostname(8),
check-permissions(8), etrn(8), newaliases(8), svcadm(8), svccfg(8),
tcpd(8)


RFC 2821 Simple Mail Transfer Protocol, John Klensin, April 2001.


RFC 2822 Internet Message Format, Pete Resnick, April 2001.


sendmail, Third Edition, Bryan Costales with Eric Allman, O'Reilly &
Associates, Inc., 2003.


http://www.sendmail.org


http://www.milter.org

NOTES

The sendmail program requires a fully qualified host name when
starting. A script has been included to help verify if the host name
is defined properly (see check-hostname(8)).


The permissions and the ownership of several directories have been
changed in order to increase security. In particular, access to
/etc/mail and /var/spool/mqueue has been restricted.


Security restrictions have been placed users using .forward files to
pipe mail to a program or redirect mail to a file. The default shell
(as listed in /etc/passwd) of these users must be listed in
/etc/shells. This restriction does not affect mail that is being
redirected to another alias.


Additional restrictions have been put in place on .forward and
:include: files. These files and the directory structure that they
are placed in cannot be group- or world-writable. See check-
permissions(8).


If you have interfaces that map to domains that have MX records that
point to non-local destinations, you might need to enable the
DontProbeInterfaces option to enable delivery to those destinations.
In its default startup behavior, sendmail probes each interface and
adds an interface's IP addresses, as well as any domains that those
addresses map to, to its list of domains that are considered local.
For domains thus added, being on the list of local domains is
equivalent to having a 0-preference MX record, with localhost as the
MX value. If this is not the result you want, enable
DontProbeInterfaces.

May 13, 2017 SENDMAIL(8)