-bm

-bm

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Be a mail sender

All versions

The -bm command-line switch (the default) causes sendmail to run once in the foreground. A list of recipients is taken from the command line (unless the -t command-line switch is used), and the message is read from the standard input and delivered.

This is the mode MUAs use when they invoke sendmail on the user 's behalf . The sendmail program processes the recipients first, then the message header, then the message body. Usually, the envelope recipients are those on the command line. But if the -t command-line switch is also used, the recipients are taken from the message header. The envelope sender is more difficult to determine:

• Trusted users, and programs running under the identity of those users, can specify the address of the sender by using the -f command-line switch ^[7] (-f) when running sendmail . Trusted users are those that are declared with a T configuration command (Section 10.8.1.1). If anyone other than a trusted user uses the -f command-line switch, an X-Authentication-Warning : header (X-Authentication-Warning:) will be added to the message to show that the sender was changed by an unauthorized user.

  ^[7] The -r is a synonym for -f , but -r is deprecated, so we don't mention it directly.

• Otherwise, sendmail tries to use the user identity of the invoking program to determine the sender.

• When generating a mail bounce message, the sender becomes the name specified by the value of the $n sendmail macro ($n), usually mailer-daemon .