Sendmail, Linuxconf & Earthlink - Help!

Hi all - 

I run a lovely little RH 7.0 box for a client (uptime > 300 days!), and
I'm stuck between a rock and a hard place. Here's the deal:

Machine is machine.domain.com.
I used Linuxconf to set up mail for domain.com and otherdomain.com,
where otherdomain.com is a Linuxconf VPOP domain, also aliased to
otherdomainaswell.com.
domain.com users POP mail off, and all is well.
otherdomain.com VPOP users POP their mail off and all is well.
Some users prefer to give out [email protected] addresses, that
mail gets put in the [email protected] VPOP box and all is well.

The Problem is:
Earthlink has decided we are an open relay, because we are vulnerable to
the Linuxconf "user%victim.com@" bug, and is now rejecting mail from us.

So I need to use m4 to create a sendmail.cf file that does what the
linuxconf one does, but doesn't allow relaying per the bug. I haven't
the foggiest idea how to proceed. Can someone point me in the right
direction? The Sendmail.org FAQ discusses virtual hosting, but not with
an eye to VPOP accounts - it seems more like aliasing. Has anyone else
had to solve this problem? Is there a way to patch the
linuxconf-generated sendmail.cf file to close the hole? Help!

Many thanks for any and all info, pointers, prayers, candle-lighting,
etc...

---- Andrew Solmssen