[Mimedefang] Powerful anti-spam rule :-)

[David Potterveld]

Hi David,

>However, there's a far more serious problem which would prevent me
>from implementing reverse-tests in MIMEDefang:  Our friends [sic] at
>Brightmail have patented this technique (US Patent 6,321,267,
>"Method and apparatus for filtering junk email")

Here's another good reason: It would turn servers with mimedefang into a
wonderful global network for DOS attacks. Imagine if someone sent emails
with forged "from" fields to many mimedefang servers, such that they all
started reverse-testing the same site with probe smtp transactions as fast
as possible... Bad news!

David Potterveld