[Mimedefang] greylisting does it still work?

[Philip Prindeville]

ADNET Ghislain wrote:
> if greylisting use a policy based on a server able to resend email, 
> could it be done in the helo phase as the source ip of the sending 
> server should be enough to greylist it.
>
> Does going further using other data than that is usefull ? (perhaps to 
> stop zombies behind a NAT router where a legitimate mail server runs ? 
> ). Have you ever seen if moving the greylist to the hello phase change 
> how filtering is efficient ?
>
>   

Don't forget that some sites have an IP address with multiple
PTR records sometimes pointing at 2 dozen domain names
or more (shouldn't be allowed, but...).

So going by IP address instead of hostname is more reliable
in this case.