Filtering attachments with Sendmail

Hey all:

I'd like to block all file attachments that end in .exe at the mail server
(end users just can't seem to overcome the temptation to run executables
that they receive as attachments. They're all a giddy crowd of idiots
currently wowing about some silly little prog that makes kittens dance
around their screens or some such crap...sorry, can you tell they're
bugging me?).

Anyway, I felt it easier to just block those. I don't care about them
subverting this by having people rename these files for sending. They're
not even that sophisticated.

Anyhow, I was looking for info. on doing this on the Sendmail site. Then
I started wondering if a global procmail recipe might be a more proper way
to do this? Anyone else doing this or have any suggestions?

To go a step further, I'd be interested in actually scanning .doc and .xls
documents that are attachments too. I run McAfee for UNIX to scan their
home directories (that Samba provides them). Ideally I'd like to stop
infected .doc files from coming in the door to begin with, though. And
maybe scan them on the way out too.

Thanks for any help! :)

Wes