I manage a sendmail box that until now has housed 2 domains.
 I set the box up as one domain, and then added another. 
All
my users were sending messages from someuser at domain1 when I
wanted them to display someuser at domain2.  I added
MASQUERADE_AS(domain2) into sendmail.mc and all was well.
Now, I've added domain 3 and 4 to this box and of course,
everything I send is from someuser at domain2 when I want it to
come from someuser at domain4.  So I've got 10 users who want
to
be @domain2, 3 who want to be at domain3 and 5 who want to
be
at domain4.  Is there a good way to manage this in Sendmail?
 I found some docs on using FEATURE(masquarde_envelope) and
FEATURE(genericstable) that appears to do what I want this
to
do, but I'm not 100% sure.  Any help would be mucho
appreciated.

-Brian