[Greylist-users] Whitelist entries and 4xx failure codes -Note to implementors

[Scott Nelson]

At 02:24 PM 9/27/04 -0400, Frank Bax wrote:
>
>I am using OpenBSD greylisting implementation that uses 450 by default, but 
>I can configure it to use 451.  My ISP provides secondary MX support and 
>that machine does not implement greylisting at all.  I am finding that a 
>significant volume of spam is arriving at mailboxes by using the secondary 
>MX.  Am I likely to see a reduction in servers using secondary MX if I 
>switch from 450 to 451?
>

Probably not.
Some spammers process the MX queue in reverse order, and that's
most likely what you're seeing.

You probably shouldn't be using a more lenient secondary MX.
Do you really need a secondary?  Mail retries by default...
Well, if you must, then a realtively easy trick is to create a final 
MX that points to a machine that always tempfails everything.
(this catches a fair amount of spam, but it's all spam that would be
caught by greylisting anyway)
Or just list your primary first and last (highest and lowest priority).



Scott Nelson <scott at spamwolf.com>