[Mimedefang] Scanning inbound mail only

[listuser at neo.pittstate.edu]

Can someone offer any suggestions for scanning inbound mail only instead
of both inbound abnd outboud mail?  I'm using MD with Sendmail 8.12.6 and
at present all mail (both from offsite to my users and from my users to
offsite) is being passed to my milters.  While bi-directional scanning is
best for AV checks, I don't want to run outbound email through
SpamAssassin.  Is there a way to tell Sendmail to either not send the
message to a certain milter if the senders is from a certain
domain/netblock, or is it possible to have MD return an OK if the sender
matches a certain domain or IP matches a netblock I define?  A few of our
business users don't like having their mail spam tagged as it leaves our
mail server.  The only way I can think of is fix this is make our MX be a
mailhub and do spam/AV scans on the mailhub.  Then I'd have to also do AV
scans on the actual mail server to do outbound AV checks.  That's not
really an option at this time though.  Any other ideas? 


Thanks
Justin