> > Just noted that we have "postfix" as a default user, and both "mail" and
> > "postfix" in /etc/group. (I don't know what maildrop is.) Why not just have
> 
> I believe that Postfix requires a unique uid and gid as part of it's
> configuration. Unfortunately, I can't find anything on the Postfix website to
> confirm this at the moment.

Since postfix (author and tools) can't possibly know what other programs
are going to run with mail (group or user) permissions (on diverse
systems), it's probably a good idea to run it under its own unique user
and group. (For example, you wouldn't want an exploited mail-ran tool to
effect your postfix queues or jobs.)

As for maildrop group, different and unrelated mail tools (courier,
postfix) use a maildrop directory and/or maildrop command (maybe SETGID
maildrop) for delivered mail or queued mail.

   Jeremy C. Reed
   http://www.reedmedia.net/