On Tue, 18 Jan 2011 22:18:20 +0000
Gary Forrest <ga...@netnorth.co.uk> wrote:
> Interesting 2 of our 3 scanning heads use a grey list system that
> uses /32 addresses as part of the process, these two servers have
> 100's of emails delayed for well over a day. Our 3rd scanning head
> uses a grey list system that is less granular /24 , this does not.
Ah, I should mention that we use a /24 for greylisting for IPv4 and a
/64 for IPv6. On the other hand, we also add a hash of the subject
into the greylisting tuple so it becomes:
{sender_address, recipient_address, sender_ip/24, subject_hash}
because we found a number of spammers bypassing greylisting but mutating
the message subject each time.
Regards,
David.
