Hello,

(I am posting this both as a summary and to know your opinion on the
second approach below)

I and others have already asked on this list in the past
how to use procmail in a virtual-domain-only (no system
accounts for email recipients) postfix environment for
small (~40/50) groups of users.

So far, the consensus was to define procmail as virtual_transport
in main.cf and master.cf, more or less in this way:

master.cf:
procmail unix - n n - - pipe
  flags=R user=nobody argv=/usr/bin/procmail -t -m /etc/procmailrc ${sender}

main.cf:

virtual_transport = procmail 

and it works. Yesterday, however, I discovered at
http://forums.site5.com/showthread.php?p=96629
an alternative approach, which _looks_ simpler.
Just define virtual aliases in this way:

me@virtualdomain1.net   : "|/absolute/path/to/procmail -m /somedir/me.virtualdomain1.net.procmailrc"
joe@virtualdomain2.com  : "|/absolute/path/to/procmail -m /somedir/joe.virtualdomain2.com.procmailrc"
jane@virtualdomain1.net : "|/absolute/path/to/procmail -m /somedir/jane.virtualdomain1.net.procmailrc"

and so on. I'll have the possibility to test it myself
only next week, but in the meantime I'd like to
ask. What do you think? Are there any caveats or corner
cases, like handling the same message to more than one
user? Which approach is better (safer| more robust|
less resource hungry)?

Thanks,
              Marco