IMP 2.2.6 & sendmail 8.9.3 & virtual domain -- bad outgoing domain name

[Pablo Sanchez]

Greetings,

I have configured my apache (1.3.17) for virtual hosting. I have IMP working 
with two domains (isore.net & lerret.com). I have changed 
imp/config/defaults.php3 for virtual domains (i.e., $SERVER_NAME). I have 
configured sendmail with virtual domain support. The emails arrive correctly 
and can be read properly. My problem is that outgoing messages all get the 
machine's primary domain name. So, if user@lerret.com sends an email it shows 
up as user@isore.net. I have searched everywhere for a fix to this. Please 
help. Thanks!