Anti-spam SMTP mods
Jonathan Hutchins
hutchins at tarcanfel.org
Tue Mar 9 19:59:30 CST 2004
On Tuesday March 9 2004 12:04 pm, Daniel Siemens wrote:
> If all admins would set up reverse DNS...
Not all can. For instance, I can't unless I buy a commercial connection,
because reverse DNS gives a RR pool hostname. It's bad enough that less than
competent admins are blocking all "dynamic" IP addresses like mine.
Blocking mail where there is _no_ valid reverse DNS is very effective. I did
have that enabled, and when I had to un-block it (per my ISP's policies), the
mail that came in was 100% spam. Some of that still gets by my beysian
filters for some reason.
I would recommend a combination of requiring that a reverse DNS exists, even
if it doesn't match the server name presented, and using other measures like
scoring mis-matched reverse DNS and dynamic IP addresses.
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