[plug] stripping potentially nasty attachments

[Craig Ringer]

> AVP Mail Scanner will look for a password in the html / plaintext and use
> anything it finds to read what's in  a password protected attachment(ie scan
> the contents for viruses). Quite nifty, but I haven't personally tried it.

Cute, but sadly bypassed by the latest viri - they send the password as
an image.

That's actually one other thing I'm looking to do on our server: if a
message contains a zip file the server couldn't decrypt and scan,
quarantine the entire message. If it's legit, the user can ask for it,
and I'll let them decrypt it in a sandbox then scan it.

Craig Ringer