The $n macro contains the name of the person who returns failed mail. Traditionally, that value is the name MAILER-DAEMON.

When delivery fails, notification of that failure is sent to the originating sender. The sendmail program generates a new message header, where the sender of the error mail message (and the sender in the envelope) is taken from $n. Then, sendmail includes the original header and all error information in the body, but might or might not include the original body in the bounce message (-R).

The $n macro must contain either a real user's name or a name that resolves to a real user through aliasing. If sendmail cannot resolve $n to a real user, the following message is logged:

Can't parse myself!

and the returned error mail message is saved in the file defined by the DeadLetterDrop option (DeadLetterDrop), if that option is defined. Otherwise, sendmail converts the qf file into a Qf file (Section 11.5).

When an error mail message is sent, $f ($f) is given the value of $n. Prior to V8.7, $n must be defined in the configuration file. Beginning with V8.7 sendmail, $n is automatically defined as MAILER-DAEMON when sendmail first starts up.

Beginning with V8.7 sendmail, you can redefine $n in your mc configuration file with a line such as this:

define(`confMAILER_NAME', `BOUNCER')

But be aware that many software programs view the name MAILER-DAEMON as special. By changing that name, you might break the way bounces are handled on your, or other, machines.

Because $n generally does not change once it is defined, you need not prefix it with $& when using it in rules.