postfix-users October 2010 archive
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postfix-users: Re: Fighting Backscatter

Re: Fighting Backscatter

From: Stan Hoeppner <stan_at_nospam>
Date: Fri Oct 22 2010 - 10:42:06 GMT
To: postfix-users@postfix.org

Jeroen Geilman put forth on 10/21/2010 4:33 PM:

> Yup.
>
> reject_unknown_client_hostname is fine for MXen and large providers, but
> it will hurt simple relaying with many false positives.

There are thousands upon thousands of web forum servers that will fall
victim to reject_unknown_client_hostname due to DNS mismatches when
attempting to send thread reply notifications and the like. I've tried
using this setting on multiple occasions over the past 5 years and it
simply causes way too many ham rejections. The last time I tried it was
rejecting replies from the Hotmail abuse servers after I'd sent some
spam reports.

There are simply too many legitimate players around the world who still
don't setup proper DNS, due to ignorance, laziness, etc. There are
plenty of anti spam methods available that can get you to blocking 99%+
of your inbound spam load without resorting to this test that blocks
much ham.

-- Stan