[Greylist-users] greylisting for exim

[martin dempsey]

I decided to give greylisting a try. The only problem is the sample 
implementation is in perl for sendmail using sendmails milter interface. I 
use exim as my MTA which is completely different. So I wrote a "C" 
implementation for exim based on the specification (not the perl code) and 
integrated it into exim using exims local_scan interface (intended for 
interfacing to virus scanners). I used the exact same mysql database layout 
since it was easy and probably a good idea to stay compatible.

Due to the way local_scan works in exim, all rejections are after the DATA 
phase. I don't think this is totally a bad thing since it costs spammers 
bandwidth which is a critical item for them. While real MTAs will also have 
to use a little more bandwidth to get the initial message through, I think 
that won't cause too many problems.

I'm currently testing my version on a low volume secondary mail server to do 
some QA and gain some experience with greylisting before moving it to my main 
machine and domains.  When I'm conviced there are no bugs, I'll be happy to 
make it publicly available to anyone wanting to use greylisting with exim.