[geeks] Postfix Ninjas?

[Jonathan C. Patschke]

I need the guidance of a Postfix ninja.

I'm stuck with residential service on cable.  Granted, this isn't
particularly horrible, especially when I recall my days of 56k dialup,
but I have the problem that a lot of people (today, especially, somone on
this list) block mail from residential IP addresses.

Ordinarily, I'd tell Postfix to use Earthlink's SMTP server as relayhost
and be done with it.  However, I'm also the backup-MX for someone whose
network is FUBAR at the moment.  If I tell Postfix to use
smtp.earthlink.net as relayhost, mail to $FUBARnetwork loops.

Is there a way I can tell Postfix to use the relayhost except when
delivering to somewhere that's in relay_domains?

-- 
Jonathan Patschke  ) "Some people grow out of the petty theft of
Elgin, TX         (   childhood.  Others grow up to be CEOs and
USA                )  politicians."                    --Phorist