Greylisting (WAS: gif attachments)

[Steve Boone]

I have noticed this behavior more from smaller ISPs.  I have been running greylisting for a while and have had no problems with delivery from the larger mail servers.  It's the people with accounts at the small town ISP that run into problems with their mail servers bouncing greylisted messages.  

I have noticed that even though I have the greylisting timeout set to 5 minutes, many servers wait anywhere from 20 minutes to several hours before retrying delivery.  I find myself having to whitelist servers for people all the time because of this (because of course, their email is "time sensitive").  All in all though, the reduction in traffic through my MailScanner is well worth the tradeoff.

Steve


-----Original Message-----
From: mailscanner-bounces at lists.mailscanner.info [mailto:mailscanner-bounces at lists.mailscanner.info] On Behalf Of Daniel Maher
Sent: Wednesday, August 23, 2006 3:02 PM
To: MailScanner discussion
Subject: RE: Greylisting (WAS: gif attachments)



> -----Original Message-----
> From: mailscanner-bounces at lists.mailscanner.info [mailto:mailscanner-
> bounces at lists.mailscanner.info] On Behalf Of Julian Field
> Sent: August 23, 2006 4:29 PM
> To: MailScanner discussion
> Subject: Re: gif attachments
> 
> 
> Try implementing greylisting on your servers. This has helped a lot with
> this problem on my systems.
> Even if you set the greylisting delay as low as 5 minutes.

My big fear w/ Greylisting is that a (legitmate) SMTP server somewhere won't respect the "try again later" code, and instead just fail to deliver the mail.  I've heard rumours that some of the larger webmail providers exhibit this behaviour.

Comments?

--
  _
 °v°  Daniel Maher
/(_)\ Administrateur Système Unix
 ^ ^  Unix System Administrator
 
Sentio aliquos togatos contra me conspirare.
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