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  • smtp mail failing

    Hi all

    I have a sbs 2000 server that is having a problem sending smtp mails to certain domains. Most mail sends fine but it appears that random mails fail to connect to the remote mail server and eventually an NDR bounces back saying unable to connect to host. I have checked with our ISP and they say we are not on any black lists or spam lists and I have achecked with one of the problem domains and they say they are not blocking us.
    If I try to connect to the mail domain by using telnet mail.problemdomain.com 25 I get the error message connect failed so something is blocking us getting to these domains and becuase its random domains is quite a problem!
    The server itself it runnign sbs 2000 with exchange sp2 and all other patches are up to date.
    thanks for any help you can offer
    Mark

  • #2
    Re: smtp mail failing

    Please do not double post. Thank you.
    1 1 was a racehorse.
    2 2 was 1 2.
    1 1 1 1 race 1 day,
    2 2 1 1 2

    Comment


    • #3
      Re: smtp mail failing

      mwelf1

      Couple of things

      1. you say you cant telnet into mail.problemdomain.com

      try telnetting in using mail.problemdomain.com's ip address instead, use nslookup to find the ip address of the problemdomain and try again.

      2. if you have some sort of antivirus/spam solution sitting in between your exchange server and the outside world it could be quarantining mails, check your config settings and view your logs to see if these mails are being dumped, ive encountered this with trends viruswall.

      mark

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      • #4
        Re: smtp mail failing

        This could also be a problem on the mail server you are trying to connect to.

        Can you telnet to other mail servers external to your domain??

        Comment


        • #5
          Re: smtp mail failing

          Hi and thanks for the responses

          I am unable to telnet to the domains using the IP address, I still get connect failed.
          I am able to connect to other external domains and indeed I can connect to the problem domains from my home pc so Im not sure where the problem is. I have contacted one of the problem domains and he sent me a test message to which I replied to and he got it! Then I tried to send him a mail about an hour later and it bounced again so very strange!
          I have checked the quarantine logs on my av and it shows nothing, the mails are just sitting in the smtp queue.
          Do I need to recreat something, DNS or SMTP connector and if so, how do I do it? What about static hosts in the hosts file, would this cure it?
          clutching at straws.....

          thanks

          Mark

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          • #6
            Re: smtp mail failing

            When these messages bounce back does your exchange box send out to other domains??

            Can you also post the message you recieve from the exchange server.

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            • #7
              Re: smtp mail failing

              mwelf1, check these:

              - check the firewall maybe there is something blocking on your firewall router connection to the problemdomain.com

              - check your DNS settings in the server IP and make sure it is pointing to the correct one. If it is pointing to local DNS, then check your local DNS forwarders and see where it is forwarding external DNS to. You can also set to forward any emails to your ISP SMTP server for that problemdomain.com only. The rest of the domain u can use DNS to send out.

              - Check the problemdomain.com MX records and try to telnet to the specified server that listed in the MX record. You should try the lowest MX record and telnet port 25 see if you can get in there.

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              • #8
                Re: smtp mail failing

                Hi Folks,
                If you are facing this problem still, this CBL blocked by the paritcular company, try to virus removal tool and then ask request the ISP to remove you IP from the Block List.

                I f you fixed this , not the solution i had given please let me know .
                - Yoga

                Comment


                • #9
                  Re: smtp mail failing

                  Also ... have you got a PTR record for your public IP? Some servers will not accept connections from an IP that fails reverse lookup.

                  Colin
                  Colin

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