Milter-greylist

Gingko wrote:
> ----- Original Message ----- 
> From: "Kai Schaetzl" <maillists@...>
> To: <milter-greylist@yahoogroups.com>
> Sent: Thursday, April 06, 2006 2:31 AM
> Subject: Re: [milter-greylist] "Dark-grey"listing dynamic IP address
> 
> 
>> wrote on Wed, 5 Apr 2006 23:58:27 +0200:
>>
>>> Filtering on reverse DNS name with three 0-255 numbers sounds therefore
>>> a good idea.
>> Very shortly you will see that there is *lots* of dynamic IP space which
>> will not fit that scheme at all. Or they don't have PTR records at all.
> 
> If they don't use this scheme, they should certainly use another one (more 
> or less recognizable), as I can't imagine them inventing a nice name for 
> every address of their dynamic address space.
> 
> Unless they don't have any reverse DNS at all, but this is by itself another 
> reason to make them suspicious ...

And you can easily match the lack of RDNS with a milter-greylist ACL, provided
you use extendedregex:

acl greylist domain /\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\]/

When there's no RDNS, sendmail passes a bracketed IP as the RDNS domain to the
milter. Otherwise it passes the RDNS domain only.