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Re: [Asrg] 7. Best Practices - DNSBLs - Article

2003-09-08 18:40:47
Brad Knowles wrote:

At 9:40 PM +0200 2003/09/08, Peter J. Holzer wrote:

     Anyone who retransmits within the thirty minute timeframe, for
 any reason, gets lambasted.

 You mean during the "blacklist" time? The sender just gets another
 4xx reply and will retry later.

    No, in this case the sender gets a personal flame from Vernon.

Izzat an RFC requirement? ;-)

Saves me having to flame them (remembering one IP that retried a single email message over two _million_ times in less than a day before I phoned him and told him to knock it off.)

 I'm more worried about senders with multiple outgoing MXs. I've
 already[0] observed one mail which took about 16 hours to be accepted,
 because the IP adresses of the sender changed apparently at random, so
 greylist entries expired several times until it managed to hit the
 greylist window with the same sender IP.

Indeed, that can be a serious problem. As can MTAs that use VERPs, since the envelope sender address will be different every time.

I need to read up on VERP.

    Greylisting most definitely is not without its problems.

As with many things, often you simply end up with an approximation.



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