[Mimedefang] Pre-Emptive Greylist entries

[David F. Skoll]

Roland Pope wrote:

> I have implemented a fiddled version of John Kirkland's MySQL
> MD-Greylist code (Thanks to Gary Funk for sending me the code), which is
> reducing SPAM, but producing complaints from users that some important
> customer emails are being delayed.

> Ie. When one of my users sends an  email from user at mynet.com to
> customer at custnet.com, I lookup custnet.com in DNS, get the IP's of the
> highest priority MX's and create a whitelist entry so that it decreases
> the chance that a reply from customer at custnet.com to user at mynet.com.
> gets delayed by the greylist code.

That assumes that custnet.com sends outbound mail from the same host
that processes inbound mail, which may not be true.

> What do you think about this idea? Does anyone have any suggestions for
> improvements?

We whitelist any host that successfully passes the "greylist hurdle".  This
whitelist lasts for 40 days, and is very good at reducing problems caused
by delayed mail, which not substantially weakening the effectiveness
of greylisting.

Regards,

David.