[Greylist-users] some comments on spamd

[Ingo Freund]

Ronald Oussoren wrote:
> 
> On 31-mei-2005, at 19:17, Graham Toal wrote:
> 
>> A final update on my saga of building a greylist server using spamd...
>>
>> We have cut down incoming spam by 90%.  We now get one spam per good
>> mail instead of 10 spams per good mail.  We reject over 80,000
>> *connections* per day from spammers, and presumably far more actual
>> spam deliveries than than (as many of the connections would have sent
>> to every user on campus - 15,000+)
> 
> 
> Do you, or anyone else, have any indication on the amount of false
> positives with greylisting? I've disabled greylisting on a site because
> several people complained that their mail didn't get through. It seems
> that some mailers are confused by a 4xx result at an unexpected location
> and drop that e-mail.
> 
> That is of course a bug in the sending MTA, but I find disappearing
> e-mail highly disconcerning even if it is only a very, very tiny  fraction
> of all e-mail.
> 
> If it weren't for those disappearing e-mail I'd never disable  greylisting,
> we also got a 90+% decrease in the amount of incoming spam and e-mail
> virusses.
> 
> Ronald

I do not use milter-sender because it dies when I try to
run it on my server and there seems to be no help available.
But I use greylisting (relaydelay from puremagic.com) and
there are only some servers in the world which cannot deal
the right way with the temporary errors which greylisting
generates.
Some of them even send error messages of undeliverable
mail to the sender but deliver the mail some time later
as they have to.
My solution is to put those servers into a whitelist.
This helps all sides and maybe in the meantime the
servers learn to handle mails as they ought to.
greylisting together with spamassassin pulled down
our spam in the mailboxes to about 2-5%.

-Ingo.

BTW: a list of servers which don't support 4xx errors
      would really help in acceptance of greylisting