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  • Port 25 Stops Responding

    Hi All..

    This is making me crazy..so I hope someone can at least point me in a direction to what could be going on!

    My server is a WIndows 2003 Sp2 Exchange 2003 SP2. Here is my problem:

    This problem started about a day or so ago: For no apparant reason, we stop receiving mail from external domains. We can send/receive internally without an issue. I checked the event viewer and there are no stop errors or warnings that would seem to be related to this problem. If I try to telnet to my server on port 25 (from an external computer), it doesnt respond. Telnetting to port 25 from an internal system works fine. If I reboot the Exchange server, the external e-mails come flying in and I can telnet to port 25. Then, after a few hours (give or take) the server stops responding on port 25..with no warning.

    Any ideas/suggestions would be greatly appreciated!

  • #2
    Re: Port 25 Stops Responding

    I would start thinking about your router and checking that out. Clearly there is not a problem with the NiC or the Exchange server (since internal is OK) but messages are not getting in from the outside world. The reboot would tell the router "hey, I'm here" and then everything flows. A second possibility is the queues on the Exchange box.

    Questions:
    What router is it?
    Do you have any problem with outgoing external messages?
    Are you sure the delayed messages are not getting to the Exchange server or are they getting stuck in a queue?
    Tom Jones
    MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
    PhD, MSc, FIAP, MIITT
    IT Trainer / Consultant
    Ossian Ltd
    Scotland

    ** Remember to give credit where credit is due and leave reputation points where appropriate **

    Comment


    • #3
      Re: Port 25 Stops Responding

      Originally posted by TheJax View Post
      Hi All..

      This is making me crazy..so I hope someone can at least point me in a direction to what could be going on!

      My server is a WIndows 2003 Sp2 Exchange 2003 SP2. Here is my problem:

      This problem started about a day or so ago: For no apparant reason, we stop receiving mail from external domains. We can send/receive internally without an issue. I checked the event viewer and there are no stop errors or warnings that would seem to be related to this problem. If I try to telnet to my server on port 25 (from an external computer), it doesnt respond. Telnetting to port 25 from an internal system works fine. If I reboot the Exchange server, the external e-mails come flying in and I can telnet to port 25. Then, after a few hours (give or take) the server stops responding on port 25..with no warning.

      Any ideas/suggestions would be greatly appreciated!
      Sounds like a Layer 1/2 issue. I would ensure correct NIC drivers for the server and no cabling issues between the exchange and router. Presumably the router has no issues port forwarding on other ports? Or is it only 25 that is effected?

      Comment


      • #4
        Re: Port 25 Stops Responding

        Thanks for the suggestions...here are the answers to your questions:

        What router is it?

        Cisco 4700

        Do you have any problem with outgoing external messages?

        No problems with outgoing mail. Just incoming.

        Are you sure the delayed messages are not getting to the Exchange server or are they getting stuck in a queue?

        I tried using the message tracking tool and am not able to find any test e-mails I have sent. After a restart of the server, and the mail has been delivered, I can find them.

        Presumably the router has no issues port forwarding on other ports? Or is it only 25 that is effected?

        The problem only is effecting port 25.

        Comment


        • #5
          Re: Port 25 Stops Responding

          It was also just reported to me that OWA stops working too. And that starts working after the restart of the server and then eventually stops.

          Comment


          • #6
            Re: Port 25 Stops Responding

            Presumably the router is performing proxy ARP for the Exchange server. Have you looked at the ARP cache on the router and on the switch that the Exchange server is connected to? Is the Exchange server dual-homed by any chance? Are you doing any type of NIC teaming on the Exchange server?

            Comment


            • #7
              Re: Port 25 Stops Responding

              After doing some testing, I've narrowed the problem down a bit...

              If I stop and restart the WWW Publishing Service e-mails start coming in, OWA works and port 25 responds. However, after awhile it just stops and I have to restart the service again.

              Comment


              • #8
                Re: Port 25 Stops Responding

                Do you have two network cards on your server -- one to the router and one to the LAN?
                Tom Jones
                MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
                PhD, MSc, FIAP, MIITT
                IT Trainer / Consultant
                Ossian Ltd
                Scotland

                ** Remember to give credit where credit is due and leave reputation points where appropriate **

                Comment


                • #9
                  Re: Port 25 Stops Responding

                  Originally posted by Ossian View Post
                  Do you have two network cards on your server -- one to the router and one to the LAN?
                  I have 1 NIC for the LAN and 1 NIC goes to our DMZ switch.

                  Thanks.

                  Comment


                  • #10
                    Re: Port 25 Stops Responding

                    Ah -- so it could be a faulty NiC going to the switch
                    Do you have a spare card and the time to shut down the server?
                    But try replacing the patch cables first -- is it one cable from server to switch or is it via a patch panel?
                    Tom Jones
                    MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
                    PhD, MSc, FIAP, MIITT
                    IT Trainer / Consultant
                    Ossian Ltd
                    Scotland

                    ** Remember to give credit where credit is due and leave reputation points where appropriate **

                    Comment


                    • #11
                      Re: Port 25 Stops Responding

                      Originally posted by joeqwerty View Post
                      Are you doing any type of NIC teaming on the Exchange server?
                      No. We do have 2 NICS, but no teaming.

                      I have not looked at the ARP table...what should I be looking for?

                      Thanks.

                      Comment


                      • #12
                        Re: Port 25 Stops Responding

                        Originally posted by Ossian View Post
                        Ah -- so it could be a faulty NiC going to the switch
                        Do you have a spare card and the time to shut down the server?
                        But try replacing the patch cables first -- is it one cable from server to switch or is it via a patch panel?
                        I do have the time to shutdown the switch. The cable goes from the server to the switch.

                        But if the NIC was bad or going bad, why would restarting the WWW Publishing Service temporarily resolve the issue?

                        Comment

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