[Mimedefang] ClamAV complement

[Cormack, Ken]

> REQUIRED: Must detect viruses with reasonable response rate for virus
definitions
> OPTIONAL: Free is good

> I'm happy with ClamAV but I think two engines are better than one, no?

For the time being, I would avoid Central Command's VEXIRA product.  Early
this year, they completely re-worked the virus-detection engine and database
format, breaking compatibility with MIMEDefang.  The latest version that
still worked, was product version 2.2.3-16, engine version 6.30.0.2, and
packlib version 2.0.4.1, from sometime last March.

Someone on this list (I don't remember who) had indicated he had started
tweaking MD to work with the new engine, but didn't get very far due to
other demands on his time.

Ken