Help beautify ugly heuristic code

[JanC]

Stuart D. Gathman schreef:

> I have a function that recognizes PTR records for dynamic IPs.  There
> is no hard and fast rule for this - every ISP does it differently, and
> may change their policy at any time, and use different conventions in
> different places.  Nevertheless, it is useful to apply stricter
> authentication standards to incoming email when the PTR for the IP
> indicates a dynamic IP (namely, the PTR record is ignored since it
> doesn't mean anything except to the ISP).  This is because Windoze
> Zombies are the favorite platform of spammers.

Did you also think about ISPs that use such a PTR record for both dynamic 
and fixed IPs?

-- 
JanC

"Be strict when sending and tolerant when receiving."
RFC 1958 - Architectural Principles of the Internet - section 3.9