SENDMAIL(1M)SENDMAIL(1M)NAMEsendmail - 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 internet‐
work 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(4) file, or in a
name service as defined by the nsswitch.conf(4) file, and aliased
appropriately. In addition, if there is a .forward file in a recipi‐
ent'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 per‐
mission 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(5), 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(1M). 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 par‐
ticular, 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 par‐
ticular, 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 ":send‐
mail" instance specification, whereas the former does not, thus repre‐
senting 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(5)). 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(1M) and svccfg(1M).
Note, however, on a system where any of the sendmail(4) files have been
customized, setting this property might not have the intended effect.
See sendmail(4) for details.
Automated Rebuilding of Configuration Files
See sendmail(4) 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(1M) and hosts_access(4) in the SUNWtcpd package.
tcpd(1M) and hosts_access(4) are not part of the Solaris man pages.
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(4) for details on which service properties can be set to auto‐
mate (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 mes‐
sage 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(1M) 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 inter‐
val. You can set this option to p, which is the only setting avail‐
able. Otherwise, this option is not set.
Mail Filter API
sendmail supports a mail filter API called "milter". For more informa‐
tion, 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 ini‐
tial 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 con‐
nections.
-bD
Runs as a daemon in the foreground, waiting for incoming SMTP con‐
nections.
-bi
Initializes the aliases(4) database. Root must own and have exclu‐
sive write permission to the /etc/mail/aliases* files for success‐
ful use of this option.
-bl
Runs as a daemon (like -bd) but accepts only loopback SMTP connec‐
tions.
-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 notifica‐
tions, which consists of the word "NEVER" or a comma-separated list
of "SUCCESS", "FAILURE", and "DELAY" for successful delivery, fail‐
ure and a message that is stuck in a queue somwhere. 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). Process‐
ing Options are described below.
-p protocol
Sets the sending protocol. The protocol field can be in form proto‐
col: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 sec‐
onds 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 unquaran‐
tines 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 transmis‐
sion. Any addresses in the argument list is suppressed. The NoRe‐
cipientAction 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 configu‐
ration file. Options are represented by a single character or by multi‐
ple 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 bene‐
ficial 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(4) 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(4) data‐
base.
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 imme‐
diately 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 send‐
mail 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 con‐
trol 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 Daemon‐
PortOptions 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.send‐
mail.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 "dou‐
ble 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 pro‐
vide 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 sup‐
presses 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 avail‐
able 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/for‐
ward/$u:$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 con‐
nect 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 num‐
ber, 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 pro‐
cesses 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 num‐
ber 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 com‐
mand. 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, restrict‐
mailq, 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 sys‐
tem, 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 aver‐
age 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 char‐
acter 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 prob‐
ably shouldn't be used on slow network links. Filename and modifi‐
cation 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(7D), 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 con‐
nections. 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 num‐
ber 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 circum‐
stances. 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. PostMil‐
ter 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 Time‐
out.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 Time‐
out.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 vari‐
able is set to this value.
TLSSrvOptions
If this option is 'V', then no client verification is per‐
formed,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 con‐
dition 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 configu‐
ration 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 HoldEx‐
pensive and DeliveryMode options so that all mail is delivered com‐
pletely in a single job so that you can see the entire delivery
process. The Verbose option should never be set in the configura‐
tion file; it is intended for command line use only.
XscriptFileBufferSize
Sets the threshold, in bytes, before a memory-bases queue tran‐
script 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 exclu‐
sive write permission. If invoked as mailq, sendmail prints the con‐
tents of the mail queue.
OPERANDS
address
address of an intended recipient of the message being sent.
USAGE
See largefile(5) for the description of the behavior of sendmail when
encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).
EXIT STATUSsendmail 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(1M), reads /etc/default/sendmail. In this file, if
the variable ETRN_HOSTS is set, the start-up script parses this vari‐
able and invokes etrn(1M) 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(4) 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 ALSOsvcs(1), biff(1B), mail(1), mailq(1), mailx(1), nice(1), check-host‐
name(1M), check-permissions(1M), etrn(1M), newaliases(1M), svcadm(1M),
svccfg(1M), fork(2), getpwnam(3C), getusershell(3C), resolver(3RESOLV),
aliases(4), hosts(4), sendmail(4), shells(4), attributes(5), large‐
file(5), smf(5), random(7D)tcpd(1M), hosts_access(4) in the SUNWtcpd package.
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 start‐
ing. A script has been included to help verify if the host name is
defined properly (see check-hostname(1M)).
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 redi‐
rected 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-permis‐
sions(1M).
If you have interfaces that map to domains that have MX records that
point to non-local destinations, you might need to enable the Dont‐
ProbeInterfaces 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.
Feb 25, 2009 SENDMAIL(1M)
