sendmail, 4th Edition

Prior to V8.7 sendmail , only the local delivery agent could cause addresses to be looked up in the aliases (5) database (Section 12.1.2). Beginning with V8.7 sendmail , any delivery agent that has an F=A delivery agent flag set will cause its $ : address to be looked up on the lefthand side of the aliases (5) file.

For example, the F=A delivery agent flag can be used to design a local-clone delivery agent that recognizes certain nonlocal addresses as local for aliasing purposes: ^[26]

^[26] This example is somewhat contrived because the same thing can be done in a more versatile manner with the mailertable feature (FEATURE(mailertable)).

R$+ <@ FIRE.WALL> $#firelocal $: @fire.wall

This allows an alias file such as the following to legally exist:

George.Washington@fire.wall: gw@internal.net

For example, as a safety net (and if the F=5 delivery agent flag is also specified), any address that is not found in the aliases (5) database will be passed to the localaddr rule set 5 (Section 19.6), where another delivery agent can be selected.

In configuration files prior to Version 6 (Section 17.5), the F=A delivery agent flag is automatically set for the local delivery agent.