AOL rejecting mail from IP's w/o reverse DNS ?

Chris Lewis clewis at
Thu Dec 4 19:24:28 UTC 2003

Suresh Ramasubramanian wrote:

> They have had this policy since several months now but it is still a 
> "may" - and does give them a good excuse to take out large IP blocks 
> that don't have proper reverse DNS assigned and emit a lot of spam.

As I understand it, they blacklist if an IP with no rDNS generates "some 
threshold of" complaints.  Not just "no rDNS" by itself.

We're doing something like that ourselves now.

Covers about 25% of all of our spam with a .025% "would be blocked if we 
didn't whitelist" rate.  Which is quite good.

A simple "no rDNS" rule causes too much trouble with our overseas 
customers.  I'm sure AOL discarded that idea for the same reason.

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