sendmail, 4th Edition

FEATURE(compat_check)—V8.12 and Later

Beginning with V8.12 sendmail, you can create a rule set that makes decisions about envelope-sender and envelope-recipient pairs with entries in the access database. To enable these checks, just add the FEATURE(compat_check) to your mc configuration file:

FEATURE(access_db)           ← must be first
FEATURE(compat_check)

Once this is enabled, you can then add entries such as the following to your access database (note that the <@ > is literal):

Compat:sender<@>recipient     keyword

Here, the Compat: prefix is literal and must be present. It is immediately followed (with no intervening spaces) by the envelope-sender address, a literal <@>, and the envelope-recipient address (where the envelope-recipient address has already undergone aliasing and processing by a user’s ~/.forward file). Neither address should be surrounded with angle braces. The address pair is followed by whitespace (spaces and tabs) and then a keyword. There are three possible keywords:

DISCARD

Mail from this sender to this recipient is accepted, and then discarded and logged. DISCARD can be followed by a colon. It can also be followed by optional text that will be logged as the reason for the discard.

TEMP:

Mail from this sender to this recipient is rejected with a temporary error (causing the message to be deferred for a later delivery attempt). This keyword must be followed by a valid 4xy SMTP code and text that describes the reason for the temporary failure.

ERROR:

Mail from this sender to this ...