mail filtering based on reverse DNS

[Sander Steffann]

Hi,

> I could see this happening, but it seems the right thing to do is to
> defend against it by implementing LRU eviction policies,
> rate-limiting, and other common mitigation techniques.  It seems such
> an attack could be undertaken even today.  (besides, what about the
> negative caching for PTRs that aren't there?)
> 
> Hmmm....

Good point.
Sander