[Greylist-users] some comments on spamd

[Ronald Oussoren]

On 31-mei-2005, at 20:41, A.L.Lambert wrote:

>> 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.
>>
>
>     Are you 100% positive sending mailers were 'dropping' the  
> messages in
> question without making any kind of bounce?   I run greylisting on a
> variety of servers (one of which crunches about 60,000 real  
> deliveries a
> day, not counting a few hundred thousand rejects), and I've had 0
> confirmed reports of lost mail that never generated a bounce of some
> kind.   I've had some user complaints stating that, but all of them
> turned out to be user errror or some kind.

I'm not 100% sure. What I saw was that a mail got rejected (4xx error)
on the first try and that the sending MTA never retried. The sending
user claimed that he never got a bounce message from his MTA. I've seen
this on several occasions.

At least one one sending MTA bounced messages when it got greylisted,
the end-user faxed me the bounce message.

BTW. I am (or rather was) using postgrey with postfix.

Luckily this site doesn't get that much spam, IIRC we're getting less
SPAM than regular messages, and the SPAM filter is keeping most of that
out.

Ronald
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