Options determine most of the sendmail program's behavior. They are declared on the command line with the -O switch:
-Oname=value
and in the configuration file with the O line:
Oname=value
The space following the O is mandatory. Prior to V8.7 sendmail, option names could be only a single character. Beginning with V8.7, option names can be multi-character. Where appropriate, the old form is listed parenthetically after the new form.
True/False options, when absent, default to false, but when present with no value, default to true. Options marked as "(safe)" can be specified on the command line without giving up root privileges.
Defines the location (and optionally the type
as type:file) of the aliases file or files.
(Was the A option, see §34.8.1,
or define ALIAS_FILE
with the m4 technique.)
Specifies the interval sendmail will wait for
the aliases database to rebuild.
(Was the a option, see §34.8.2,
or define confALIAS_WAIT
with the m4 technique.)
(safe) allows sendmail to accept an SMTP HELO or EHLO that is not followed by a hostname (see §34.8.3).
Allows sendmail to automatically rebuild the aliases database.
(Was the D option, see §34.8.4,
or define confAUTO_REBUILD
with the m4 technique.)
Specifies the unquoted space replacement character char.
(Was the B option, see §34.8.5,
or define confBLANK_SUB
with the m4 technique.)
(safe) tells sendmail to check the right side of aliases
in the aliases file in addition to the normal
left side checks.
(Was the n option, see §34.8.6,
or define confCHECK_ALIASES
with the m4 technique.)
(safe) states the number of recipients that will be delivered
between checkpoints (flushes to disk) of the qf file.
(Was the C option, see §34.8.7,
or define confCHECKPOINT_INTERVAL
with the m4 technique.)
Sets the multiplication factor for calculating
priority increments.
(Was the z option, see §34.8.8,
or define confWORK_CLASS_FACTOR
with the m4 technique.)
(safe) tells sendmail to allow colons in addresses,
thus disabling recognition of :;
list addresses - DECnet
::
is always allowed
(see §34.8.9,
or define confCOLON_OK_IN_ADDR
with the m4 technique).
Stipulates the number of simultaneous open SMTP connections
sendmail will maintain during delivery.
(Was the k option, see §34.8.10,
or define confMCI_CACHE_SIZE
with the m4 technique.)
Stipulates the duration of time any given open, but when idle,
SMTP connection will be maintained.
(Was the K option, see §34.8.11,
or define confMCI_CACHE_ TIMEOUT
with the m4 technique.)
Specifies the maximum number of incoming connections
that will be accepted per second. Additional connections
are accepted progressively more slowly
(see §34.8.12,
or define confCONNECTION_ RATE_THROTTLE
with the m4 technique).
Sets the daemon TCP/IP port options.
Available options are:
Addr
is the network to accept connections from;
Family
is the type of network;
Listen
is the size of the listen(2) queue;
Port
is the port on which sendmail should listen;
ReceiveSize
is the size of the TCP/IP receive buffer;
and SendSize
is the size of the TCP/IP send buffer.
(Was the O option, see §34.8.13,
or define confDAEMON_ OPTIONS
with the m4 technique.)
(safe) Defines the character set that will be
listed in the Content-Type:
header, for MIME 8- to 7-bit conversion
(see §34.8.14,
or define confDEF_CHAR_ SET
with the m4 technique).
Specifies the default non-root identity for sendmail.
The user may be a numeric uid or a login name.
If group is omitted, user is looked up in
the passwd(5) database, and that gid is used.
Otherwise, group may be a numeric gid or a group name.
(Was the u and g options, see §34.8.15,
or define confDEF_ USER_ID
with the m4 technique.)
(safe) sets the delivery mode that sendmail will run as.
Select mode from:
background
to run asynchronously;
interactive
to run synchronously;
queue-only
to queue, rather than deliver, all mail;
or deferred
to queue all mail without doing
any DNS lookups.
(Was the d option, see §34.8.16,
or define confDELIVERY_MODE
with the m4 technique.)
(safe) specifies how long to sleep after a connection failure.
If non-zero, sleeps that interval then tries again
(see §34.8.17,
or define confDIAL_DELAY
with the m4 technique).
Prevents CNAME expansion when looking up
MX records
(see §34.8.18,
or define confDONT_ EXPAND_CNAMES
with the m4 technique).
Suppresses use of the initgroups(3) call to
look up additional group memberships
(see §34.8.19,
or define confDONT_INIT_GROUPS
with the m4 technique).
Prevents sendmail from short-circuiting source routes.
(Was the R option, see §34.8.20,
or define confDONT_PRUNE_ROUTES
with the m4 technique.)
Specifies the address to which an error message should be sent
if there is an error sending an error message
(see §34.8.21,
or define confDOUBLE_BOUNCE_ADDRESS
with the m4 technique).
(safe) specifies how to convert unlabeled MIME input.
Select from:
mimify
to force conversion of 8BITMIME to 7-bit;
pass
to pass unlabeled 8-bit input through as-is;
or strict
to reject unlabeled 8-bit input.
(Was the 8 option, see §34.8.22,
or define confEIGHT_BIT_HANDLING
with the m4 technique.)
(safe) specifies text or a file's contents to insert at
the top of bounced messages.
If the description starts with a slash, it is
taken as the full pathname of a file, otherwise
the description is taken as literal text.
The text is macro-expanded during interpolation.
(Was the E option, see §34.8.23,
or define confERROR_MESSAGE
with the m4 technique.)
(safe) specify mode of error handling.
Select from:
m
to mail error notification to the sender no matter what;
e
to act just like m
, but to always exit with a zero exit status;
p
to print error messages (the default);
q
to remain silent about all delivery errors;
or w
to write errors to the sender's terminal screen.
(Was the e option, see §34.8.24,
or define confERROR_ MODE
with the m4 technique.)
Specifies the host to send mail to when all connections to
the actual MX hosts have failed.
(Was the V option, see §34.8.25,
or define confFALLBACK_MX
with the m4 technique.)
Causes queue files to be processed individually to
lessen the impact on small-memory machines.
(Was the Y option, see §34.8.26,
or define confSEPARATE_PROC
with the m4 technique.)
Sets the ~/.forward search path.
Each file name is macro-expanded, then tried.
Each is tried in turn until one can be read, whereupon
it is the ~/.forward for that local recipient.
(Was the J option, see §34.8.27,
or define confFORWARD_PATH
with the m4 technique.)
Specifies the location of the file that
contains help messages for the SMTP (and ESMTP)
HELP command, and usage for the -bt rule-testing
command.
(Was the H option, see §34.8.28,
or define HELP_FILE
with the m4 technique.)
Tells sendmail to queue rather than deliver messages
that will be delivered by "expensive" delivery agents (those
with an F=e flag set).
(Was the c option, see §34.8.29,
or define confCON_ EXPENSIVE
with the m4 technique.)
Specifies an alternative for the /etc/hosts file
(see §34.8.30, or define
confHOSTS_FILE
with the m4 technique).
Specifies the directory in which sendmail should
store persistent host status. If specified, this also
enables the keeping of that status. A relative name is
relative to the queue directory
(see §34.8.31,
or define confHOST_STATUS_DIRECTORY
with the m4 technique).
(safe) tells sendmail to ignore leading dots in the message body.
(Was the i option, see §34.8.32,
or define confIGNORE_DOTS
with the m4 technique.)
(safe) sets the logging level, where a level of:
0-6
logs progressively less serious problems;
7
logs delivery failures;
8
logs delivery successes;
9
logs deferred delivery;
10-11
logs database and nis lookups;
12
logs SMTP connects;
13
logs questionable permissions;
14
logs connection refusals;
15
logs all incoming and outgoing SMTP commands;
and 16-98
logs progressively more detailed debugging
information.
On the command line, you can only increase the logging level.
(Was the L option, see §34.8.33,
or define confLOG_LEVEL
with the m4 technique.)
Enables so called "Fuzzy"
matching of the recipient in the gecos field
of the passwd(5) database.
(Was the G option, see §34.8.34,
or define confMATCH_ GECOS
with the m4 technique.)
Specifies maximum number of children that sendmail will
fork to process inbound connections. Does not limit forked
children that process the queue
(see §34.8.35,
or define confMAX_DAEMON_CHILDREN
with the m4 technique).
Sets the maximum number of times a message may be relayed
through mail-handling sites (the maximum hop count).
(Was the h option, see §34.8.36,
or define confMAX_HOP
with the m4 technique.)
Specifies the maximum size (in bytes) of an incoming
message that sendmail will accept
(see §34.8.37,
or define confMAX_MESSAGE_SIZE
with the m4 technique).
(safe) specifies the maximum number of queued messages that sendmail
will process from a queue in a given queue run
(see §34.8.38,
or define confMAX_QUEUE_RUN_SIZE
with the m4 technique).
(safe) causes a copy of the message to be sent to the sender too, when
the sender is one of the recipients listed in an alias or
mailing list.
(Was the m option, see §34.8.39,
or define confME_TOO
with the m4 technique.)
(safe) defines minimum number of free disk blocks that
must be available when a message's size is stated
with the SIZE keyword to the ESMTP MAIL
command.
(Was the b option, see §34.8.40,
or define confMIN_FREE_BLOCKS
with the m4 technique.)
(safe) skips processing of a queued file if the last time
it was processed is sooner than the interval specified
(see §34.8.41,
or define confMIN_ QUEUE_AGE
with the m4 technique).
Allows sendmail to quote nonaddress characters in an address, as required by RFC822 (see §34.8.42).
(safe) specifies how to handle the situation of no recipients being
specified in the header (as would be the case when all recipients
were specified in Bcc:
headers).
Select from:
add-apparently-to
, which adds an Apparently-To:
header;
add-bcc
, which adds an empty Bcc:
header;
add-to
, which adds an empty To:
header;
add-undisclosed
, which adds a To: undisclosed-recipients:;
header;
or none
, which passes the message unchanged
(see §34.8.43,
or define confNO_RCPT_ACTION
with the m4 technique).
(safe) causes sendmail to insert commas between the recipients
listed in a space-delimited list of recipients.
(Was the o option, see §34.8.44,
or define confOLD_STYLE_HEADERS
with the m4 technique.)
Sets token-separation operators to the list of characters
given.
(Was the $o macro, see §34.8.45,
or define confOPERATORS
with the m4 technique.)
Enables the user, whose email address is given, to receive
an extra copy of every bounce message.
(Was the P option, see §34.8.46,
or define confCOPY_ERRORS_TO
with the m4 technique.)
(safe) increases privacy and security of the daemon.
Each option adds to earlier options. Select from:
authwarnings
, which enables X-Authentication-Warning:
headers;
needexpnhelo
, which requires SMTP HELO before EXPN;
needmailhelo
, which requires SMTP HELO before MAIL;
needvrfyhelo
, which requires SMTP HELO before VRFY;
noexpn
, which disables all SMTP EXPN commands;
novrfy
, which disables all SMTP VRFY commands;
and goaway
, which enables all the preceding.
Also select from:
public
, which means none of the preceding;
restrictmailq
, which restricts who may run mailq(1);
restrictqrun
, which restricts who may process the queue;
and noreceipts
, which disables sending of return-receipt mail.
(Was the p option, see §34.8.47,
or define confPRIVACY_ FLAGS
with the m4 technique.)
Specifies the full pathname of the queue directory.
(Was the Q option, see §34.8.48,
or define QUEUE_DIR
with the m4 technique.)
Sets the factor for high-load queuing. When a message is received, the decision to deliver or to queue it is based on the formula:
priority > QueueFactor / (load - QueueLA + 1)
If the priority of the message is greater than the result of this
formula, where load
is the current load average, the message
is delivered. (Was the q option, see §34.8.49,
or define confQUEUE_FACTOR
with the m4 technique.)
Specifies the load average above which queue runs will be skipped.
This is also used in the formula shown above for QueueFactor.
(Was the x option, see §34.8.50,
or define confQUEUE_LA
with the m4 technique.)
(safe) specifies how to presort the queue.
Select from:
host
to sort by recipient host, lock status, and priority;
priority
for a simple sort of the message priorities;
or time
to sort based on submission time
(see §34.8.51,
or define confQUEUE_ SORT_ORDER
with the m4 technique).
Limits the life of a queued message to the interval specified.
The first delivery failure after that interval is exceeded
causes the message to bounce. (Was the T option; deprecated,
use the Timeout.queuereturn
option instead.)
Penalizes large recipient lists by multiplying the number of
recipients by this factor when determining a message's priority.
(Was the y option, see §34.8.53,
or define confWORK_RECIPIENT_FACTOR
with the m4 technique.)
Tells sendmail to refuse incoming SMTP connections
when the load average exceeds this specified load.
(Was the X option, see §34.8.54,
or define %confREFUSE_LA
with the m4 technique.)
Tunes DNS lookups by specifying an arg, or args, such as:
+AAONLY
, which turns on the AAONLY name server option
(Authoritative Answers Only);
and
-DNSRCH
, which turns off the DNSRCH
name server option (search the domain path).
(Was the I option, see §34.8.55,
or define confBIND_OPTS
with the m4 technique.)
Sets the amount to increment a job's priority each time
a message fails to be delivered.
(Was the Z option, see §34.8.56,
or define confWORK_ TIME_FACTOR
with the m4 technique.)
Runs sendmail as a user other than root.
The user may be a numeric uid or a login name.
If group is omitted, user is looked up in
the passwd(5) database and the primary gid is used.
Otherwise, group may be a numeric gid or a group name
(see §34.8.57,
or define confRUN_AS_USER
with the m4 technique).
Sets the pathname to a directory that is safe for file writes. The
sendmail program does a chroot(2) to that
directory before writing to files.
Also prevents writing to other than plain files,
with the exception of /dev/null
(see §34.8.58,
or define confSAFE_ FILE_ENV
with the m4 technique).
Prevents sendmail from removing
UNIX mailbox-style From lines from input.
(Was the f option, see §34.8.59,
or define confSAVE_FROM_LINES
with the m4 technique.)
(safe) Tells sendmail it may return error messages (bounced mail
notifications) in MIME format.
(Was the j option, see §34.8.60,
or define confMIME_ FORMAT_ERRORS
with the m4 technique.)
Specifies the location of the switched-services file.
Under Solaris, DEC OSF/1, and Ultrix, this
option is ignored, and the system file automatically used.
A switch-services file defines how and in what order
services, such as alias, host, and user information,
will be looked up
(see §34.8.61,
or define confSERVICE_SWITCH_FILE
with the m4 technique).
(safe) Forces sendmail to clear the high-bit of each byte of a message's
body that it reads.
(Was the 7 option, see §34.8.62,
or define confSEVEN_ BIT_INPUT
with the m4 technique.)
(safe) Tells sendmail to strip all newline characters
from From:
headers
(see §34.8.63).
Ensures that only a single sendmail
will ever be delivering to a given host at a given time.
Requires that the HostStatusDirectory
option be set
(see §34.8.64,
or define confSINGLE_THREAD_ DELIVERY
with the m4 technique).
Specifies the SMTP greeting message.
(Was the $e macro, see §34.8.65,
or define confSMTP_ LOGIN_MSG
with the m4 technique.)
Specifies the location of the statistics file
(usually sendmail.st preceded by an
appropriate path).
(Was the S option, see §34.8.66,
or define STATUS_FILE
with the m4 technique.)
(safe) Ensures additional reliability by forcing all messages to
be queued, even if they could be directly delivered.
(Was the s option, see §34.8.67,
or define confSAFE_QUEUE
with the m4 technique.)
Sets the default permissions (in octal) for created temporary files.
(Was the F option, see §34.8.68,
or define confTEMP_FILE_MODE
with the m4 technique.)
Sets the time zone to that specified. If zone is absent,
imports the TZ variable from the environment.
If the entire option
is missing, the default is to unset the TZ environmental variable and
use the system default.
(Was the t option, see §34.8.69,
or define confTIME_ZONE
with the m4 technique.)
Sets the timeout for an event to the interval specified. See the section "The Timeout Option" for details.
Tells sendmail to connect directly to the A record for
a host when the best MX record points to this host.
(Was the w option, see §34.8.71,
or define confTRY_NULL_MX_LIST
with the m4 technique.)
Defines the format for the UUCP-style From
line.
(Was the $l macro, see §34.8.72,
or define confFROM_LINE
with the m4 technique.)
Tells sendmail to check group write permissions
on files that it is taking addresses from, and to reject
those files (and hence the addresses)
when such group write permissions are found
(see §34.8.73,
or define confUNSAFE_GROUP_WRITES
with the m4 technique).
(safe) Allows error notification
to be sent to the address listed in the Errors-To:
header
in addition to that sent to the envelope sender.
(Was the l option, see §34.8.74,
or define confUSE_ ERRORS_TO
with the m4 technique.)
Specifies the location of the database file that will be
used for User Database lookups.
(Was the U option, see §34.8.75,
or define confUSERDB_SPEC
with the m4 technique.)
(safe) Causes sendmail to run in verbose mode. (Was the v option, see §34.8.76.)