From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gavin Hamill <gdh@acentral.co.uk>
Subject: Allow only SMTP 'callback'
Date: Mon, 10 Jan 2005 10:30:59 +0000
Message-ID: <200501101030.59086.gdh@acentral.co.uk>
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To: netfilter@lists.netfilter.org

Hello :)

Normally I permit only port 80 incoming to our webservers, but since each 
webserver also sends out booking-complete confirmation emails, I would like 
to also enable incoming port 25 for those remote mail servers who 'call back' 
to check that the envelope sender  / HELO address is truly a reachable mail 
server.

I don't particularly want to leave port 25 simply open, but only for those 
hosts with whom an outgoing port 25 connection is already established with.

Is this possible?

Cheers,
Gavin.