Milter-greylist

manu@... wrote:
> Bob Smith <bsmith@...> wrote:
> 
>> This is uncommon enough that a 
>> check on every incoming message is way too drastic.
> 
> Well, if you perform multiple similar DNS requests, they should not go
> beyond the cache of your DNS server...

It's a dyndns.org hostname, the TTL is very short as a result, so the cache 
isn't going to help you.