[Mimedefang] Using MD to limit parts passed to SA

[Sean McCrohan]

I'm presently using procmail to call SA directly, but I'm considering
changing over to using MIMEDefang. My main interest is reducing the 
size of the messages that SA is scanning, to improve performance - 
I don't want to drop the heavy parts (images, binary attachments, etc)
entirely (at least, not in all cases), but I don't want them included
in the message that gets passed to SA. 

I think I see how that'd be done - build a version of the message for
scanning by appending the 'good' parts in filter, then call SA with
that version in filter-end, with the results applied to the original
message. But has anyone else done something like this, or is there a 
better way to manage it? I'd rather steal something that already 
works, if it exists :)

--S