OSEC

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Re: Sender access restrictions by connecting back to the MX/A server(s)

From: Wietse Venema (wietseporcupine.org)
Date: Thu Oct 02 2003 - 07:20:04 CDT

Guido Van De Velde:
> Furthermore such a check involves everytime on acceptance a backwards
> connection. This ISP who does this here, is all day long opening and
> closing connections to our incoming mailservers without sending mail. I

Then their implementation is broken.

For example, Postfix caches the result of successful probes and
then repeats the probe no more than once a week.

        Wietse