[Mimedefang] Filtering for external e-mail addresses

[Matthew Rossiter]

I'm using RedHat Linux 9.0, sendmail-8.12.11, Mail-SpamAssassin-2.63, and
MimeDefang 2.39 along with the latest version of procmail.

Everything is working perfectly.  Can anyone recommend a good way to
filter out mail aliases as well?  In other words if my /etc/mail/aliases
file has 'bob: bob at yahoo.com' in it.  Can the mail get sent through the
filter first before getting redirected?

I was thinking of maybe creating a user called aliasfilter and have all
the aliased mail sent to it first and then create a .procmailrc file which
sends it to the appropriate email address based on the TO: address.

But maybe there's a much simpler and more effective method.  Right now,
none of my aliases going to external email addresses are getting filtered.

Ideas?

Matt