sendmail(1M)

A mode selected from those described in the "Modes" subsection below. Only one mode can be specified. The default is -bm.

The address of a recipient. Several addresses can be specified.

A flag selected from those described in the "Flags" subsection below. Several flags can be specified.

Go into ARPANET mode. All input lines must end with a CR-LF, and all messages will be generated with a CR-LF at the end. Also, the ``From:'' and ``Sender:'' fields are examined for the name of the sender.

Run as a daemon. sendmail will fork and run in background listening on socket 25 for incoming SMTP connections.

Run as a daemon, but run in foreground.

Print the persistent host status database.

Purge the persistent host status database.

Initialize the alias database for the mail aliases file. newaliases is identical to sendmail -bi. See newaliases(1M).

Deliver mail in the usual way (default).

Print a listing of the mail queue. mailq is identical to sendmail -bp. See mailq(1).

Use the SMTP protocol as described in RFC821 on standard input and output. This flag implies all the operations of the ba flag that are compatible with SMTP.

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

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

Set the body type, 7BIT or 8BITMIME.

Use alternate configuration file. sendmail refuses to run as root if an alternate configuration file is specified.

Set debugging value to X.

Set the full name of the sender.

Sets the name of the ``from'' person (i.e., the sender of the mail) to name. If the user of the -f option is not a ``trusted'' user (normally root, daemon, and network) and if the name set using the -f option and the login name of the person actually sending the mail are not the same, it results in an X-Authentication-Warning in the mail header.

Set the hop count to N. The hop count is incremented every time the mail is processed. When it reaches a limit, the mail is returned with an error message, the victim of an aliasing loop. If not specified, ``Received:'' lines in the message are counted.

Ignore dots alone on lines by themselves in incoming messages. This should be set if you are reading from a file.

Do not do aliasing.

Set delivery status notification conditions. The valid conditions with which dsn can be set are as follows:

Set option option to a specified value. Options are described below in ""Processing Options."

Set option x to the specified value. Options are described below in "Processing Options."

Set the name of the protocol used to receive the message. This can be a simple protocol name such as ``UUCP'' or a protocol and hostname, such as ``UUCP:ucbvax''.

Process saved messages in the queue at given intervals. If time is omitted, process the queue once. time is given as a tagged number, with s being seconds, m being minutes, h being hours, d being days, and w being weeks. For example, -q1h30m or -q90m would both set the timeout to one hour thirty minutes. If time is specified, sendmail will run in background. This option can be used safely with bd.

Limit processed jobs to those containing substr as a substring of the queue id.

Limit processed jobs to those containing substr as a substring of one of the recipients.

Limit processed jobs to those containing substr as a substring of the sender.

An alternate and obsolete form of the f flag.

Set the amount of the message to be returned if the message bounces. The values that can be set for return are as follows:

Read message for recipients. To:, Cc:, and Bcc: lines will be scanned for recipient addresses. The Bcc: line will be deleted before transmission.

Initial (user) submission. This flag should always be set when sendmail is called from a user agent such as mail or elm. This flag should never be set when called from a network delivery agent such as rmail.

Go into verbose mode. Alias expansions will be announced, etc.

Set the original envelope identification. This is propagated across SMTP to servers that support DSN's (delivery status notification) and is returned in DSN-compliant error messages.

Log all traffic in and out of mailers in the indicated log file. This should only be used as a last resort for debugging mailer bugs. It will log a lot of data very quickly.

Stop processing command flags and use the rest of the arguments as addresses.

Use alternate alias file.

If set, sendmail logs transient error messages as LOG_ALERT messages at Loglevel>=2. If not set, sendmail logs transient error messages as LOG_INFO messages at Loglevel>8.

On mailers that are considered ``expensive'' to connect to, do not initiate immediate connection. This requires queuing.

Checkpoint the queue file after every N successful deliveries (default 10). This avoids excessive duplicate deliveries when sending to long mailing lists interrupted by system crashes.

Set the delivery mode to x. Delivery modes are

Set error processing to mode x. Valid modes are

If the text of the message is not mailed back by modes m or w and if the sender is local to this machine, a copy of the message is appended to the file dead.letter in the sender's home directory.

Save UNIX -style From lines at the front of messages.

The maximum number of times a message is allowed to ``hop'' before it is considered in a loop.

Do not take dots on a line by themselves as a message terminator.

Send error messages in MIME format.

Set connection cache timeout.

Set connection cache size.

The log level.

Send to ``me'' (the sender) also if the sender is in an alias expansion.

Validate the right hand side of aliases during a newaliases command. See newaliases(1M).

If set, this message may have old style headers. If not set, this message is guaranteed to have new style headers (i.e., commas instead of spaces between addresses). If set, an adaptive algorithm is used that will correctly determine the header format in most cases.

Select the directory in which to queue messages.

Save statistics in the named file.

Set the timeout on undelivered messages in the queue to the specified time. After delivery has failed (e.g., because of a host being down) for this amount of time, the failed messages will be returned to the sender. The default is three days.

If set, a user database is consulted to get forwarding information. You can consider this an adjunct to the aliasing mechanism, except that the database is intended to be distributed; aliases are local to a particular host.

Fork each job during queue runs. May be convenient on memory-poor machines.

Strip incoming messages to seven bits.

Set the handling of eight bit input to seven bit destinations. Mode can be set to the following values

Sets how long a job must ferment in the queue in between attempts to send it.

Sets the default character set used to label 8-bit data that is not otherwise labeled.

If opening a connection fails, sleep for sleeptime seconds and try again. Useful on dial-on-demand sites.

Set the behaviour when there are no recipient headers (To:, Cc: or Bcc:) in message to action. The different values that can be set for action are

Sets the maximum number of children that an incoming SMTP daemon will allow to spawn at any time to N.

Sets the maximum number of connections per second to the SMTP port to N.

If set, causes sendmail to rebuild the alias database when needed. Setting this option may cause excessive overhead and is not recommended.

If set, this option is to turn off the inclusion of all the interface names in $=w on startup. In particular, if you have lots of virtual interfaces, this option will speed up startup. However, unless you make other arrangements, mail sent to those addresses will be bounced. This is useful for sending mail to hosts which have dynamically assigned names.

This options allows you to bypass some of sendmail file security checks at the expense of system security. This should only be used if you are absolutely sure you know the consequences. The available options for DontBlameSendmail are as follows:

This can be set to true to prevent program deliveries from picking up extra group privileges.

This option limits the number of recipients, no_of_recipients that will be accepted in a single SMTP transaction. After this number is reached, sendmail starts returning "452 Too many recipients" to all RCPT commands. This can be used to limit the number of recipients per envelope (in particular, to discourage use of the server for spamming). Note: a better approach is to restrict relaying entirely.

This option allows to specify a maximum length of the sum of all headers, max_header_length . This can be used to prevent a Denial-of-Service(DoS) attack.

If set, causes sendmail to do a setuid to that user early in processing to avoid potential security problems. However, this means that /var/spool/mqueue directory owned by the user and all .forward and :include: files must be readable by that user, and all files to be written must be writable by that user, and all programs will be executed by that user. It is also incompatible with the SafeFileEnvironment option. In other words, it may not actually add much to security. However, it should be useful on firewalls and other places where users do not have accounts and the aliases file is well constrained.

If set, files named as delivery targets must be regular files in addition to the regular checks. Also, if the option is non-null, then it is used as the name of a directory that is used as a chroot(2) environment for the delivery; the file names listed in an alias or forward should include the name of this root.

This option can take two values (host or priority and time ). Based on that, the queue will be sorted.

The available values for flag are

By default, authwarnings and restrictqrun are enabled.