better blocking at MTA level (off-topic)

[Alex Neuman van der Hans]

Koopmann, Jan-Peter wrote:
> Attention: Just because you choose 5 minutes does not mean there will be
> a 5 minute delay. Most MTAs I know (at least old Exchange installations
> and yes there are dumb people out there using Exchange as the only MTA!)
> use a 15 minute retry cycle. This results in at least 15 minutes delay
> if not more. And we have several clients not liking that idea. :-(
>   
What I've done in the past is to create a report from the MySQL data 
gathered by MailWatch installations (even if you don't actively use it, 
at least you have a pretty good database that lists all the 
characteristics of incoming and outgoing mail) and see, for example, 
who's sent the client more than a few e-mails (or who the MX is for 
whoever the client sent more than a few e-mails to) in order to 
pre-build a "don't use greylisting with" list, and feed it to the 
greylist milter. That way at least you begin greylisting "relative 
unknowns" and not greylisting "relatively known" senders.