Re: [vps-mail] Customer reactions to greylisting?

[Scott Wiersdorf <scottw@xxxxxxxxxxxx>]

On Tue, May 10, 2005 at 02:05:43PM -0400, Brian Haines wrote:
> <quote guru="Bennett Lanford">
> The only possible drawback is that when a sender *first* sends an e-mail to
> a particular recipient on your server, your server returns a
> *temporary* failure response, forcing the sending server to queue the mail
> until its next queue run (typically 20-60 minutes). Compliant SMTP servers
> will all queue the mail and deliver it within that time period.

<snip>

I've seen other problems, though, when legitimate businesses use
broken SMTP implementations, or proxies where the sender IP keeps
changing. That's the reason for the long list at the bottom of the
greylist.conf file: these are known broken-but-legitimate clients.

The catch is that the list isn't exhaustive, so you need to be on your
guard for your users again. One approach would be to only enable
certain domains on your system that you're comfortable with, allowing
users to opt-in.

When it's on and working, it works better than *any* other tool I've
used for UCE. there's nothing quite like the feeling of blocking spam
(no relation to SPAM) right at the SMTP connection.

Scott
-- 
Scott Wiersdorf
scottw@xxxxxxxxxxxx
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