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    Test for open relay

    Scheduled Pinned Locked Moved Firewalling
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    • S Offline
      skeating
      last edited by

      How can I test if my firewall is being used for an email relay? I have landed on a couple of block lists, with the IP for the firewall being listed as the culprit. There is a mail server behind the firewall, and I have tested that and confirmed it is not relaying. That only leaves the firewall to be checked.

      Stephen Keating

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      • dotdashD Offline
        dotdash
        last edited by

        Unless you installed postfix, it's not going to be the firewall. Probably some kind of spam mailer on a workstation. Add a rule to allow outbound smtp from your mail server, then block and log all other smtp traffic from the lan.

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        • S Offline
          skeating
          last edited by

          Thanks

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          • KOMK Offline
            KOM
            last edited by

            MXToolbox has a bunch of tools, including an open relay test during its diagnostics:

            http://mxtoolbox.com/

            http://mxtoolbox.com/diagnostic.aspx

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