I tested my smtp (postfix) mail system with this tool: http://mxtoolbox.com/
Apparently everything is fine, including my reverse DNS and my HELO name (Reverse DNS matches SMTP Banner). It also confirms that my server is NOT an open mail relay.
I checked my apache logs and my mail logs (mail.err, mail.info, mail.log). Everything seemed normal.
As on any other system, my web scripts might have been abused, so I checked last week for some irregular traffic with the probe TCPDUMP listening on port 25: I saw very little traffic, and apparently nothing wrong.
Please also note that my server is behind a router, but is the only one to use on this Fixed IP. No wireless access authorised.
As i have seen that when we are listed on CBL, it is often because of some Proxy or transparent proxy being installed on the mail server, that is why i am wondering if the problem is coming from this Tproxy apache 2 daemon.
And the only way i found out is to shut it down before asking a new CBL delisting.
Does anyone know how to shut down Tproxy ?
The only way to stop it for the moment is to stop my apache2 server, which is not very convenient !!! ;-)
Thanks in advance for your help.