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Exchange 2003 - Unable To Receive External Emails

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  • Exchange 2003 - Unable To Receive External Emails

    I've recetly set up an exchange 2003 SP2. However, I am able to send and receive internal emails; I am able to send external emails but i cannot receive any external emails.

    i've created user accounts and the email addresses are automatically assigned by the exchange server as per the recipient policy
    I can connect to the exchange server via outlook, and i can send emails internally and also send external emails, but i cannot receive any external emails.

    The ISP router has ports open to allow SMTP (25), HTTPS(443), POP3(110), andRemote Desktop(3389), which all seem to be working fine.

    The MX record for the domain is pointing to server.domain.co.uk which is pointing to the clients external static IP for the router, so i'm a bit confused as to why its not working.

    Can you tell me if i've done anything wrong, what i need to change and how i can possible get this exchange server working 100%

  • #2
    Re: Exchange 2003 - Unable To Receive External Emails

    Do you have a NAT rule that translates the ip address of server.domain.co.uk to the internal ip address of the Exchange server?

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    • #3
      Re: Exchange 2003 - Unable To Receive External Emails

      Can you telnet to port 25 externally?
      cheers
      Andy

      Please read this before you post:


      Quis custodiet ipsos custodes?

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      • #4
        Re: Exchange 2003 - Unable To Receive External Emails

        YES... I have a NAT rule set up. Could you possibly run the telnet session from your end please?

        SERVER NAME - modunserver
        DOMAIN NAME - modun.co.uk

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        • #5
          Re: Exchange 2003 - Unable To Receive External Emails

          Telnet fails to connect. An nslookup gives "can't find modunserver.modun.co.uk: Non-existent domain", so it looks like a DNS problem to me. Do you have an A record for the server in your public DNS?

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          • #6
            Re: Exchange 2003 - Unable To Receive External Emails

            YES, I do have an A record assigned but with content of my internal static ip of my exchange server.

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            • #7
              Re: Exchange 2003 - Unable To Receive External Emails

              You need an A record in your public DNS namespace that resplves to the public ip address that you're NAT'ing to the internal ip address of the Exchange server.

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              • #8
                Re: Exchange 2003 - Unable To Receive External Emails

                Please See attached A and MX records information and configuration... I did confirm with my domain registrar it was correct, is it?
                Attached Files

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                • #9
                  Re: Exchange 2003 - Unable To Receive External Emails

                  No, the A record for mail (192.168.1.5)is a private ip address and is not routable. You need to change that to a public, routable ip address from the block you got from your ISP.

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                  • #10
                    Re: Exchange 2003 - Unable To Receive External Emails

                    So, my A record should have my public IP whilst my MX record should be my internal/Private IP for my exchange server?

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                    • #11
                      Re: Exchange 2003 - Unable To Receive External Emails

                      Or rather my MX record should remain as it is?

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                      • #12
                        Re: Exchange 2003 - Unable To Receive External Emails

                        No. External email servers can't connect to your MX record if it's a private ip address because it's not routable. Here's what you need:

                        A record = mail.modun.co.ok = 12.12.12.12 (whatever public ip address you get from your ISP)

                        MX record = mail.modun.co.uk

                        Nat rule = 12.12.12.12 goes to 192.168.1.5
                        Firewall rule = SMTP traffic allowed to go to 192.168.1.5

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                        • #13
                          Re: Exchange 2003 - Unable To Receive External Emails

                          Moved to exchange forum where it belongs.
                          Marcel
                          Technical Consultant
                          Netherlands
                          http://www.phetios.com
                          http://blog.nessus.nl

                          MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
                          "No matter how secure, there is always the human factor."

                          "Enjoy life today, tomorrow may never come."
                          "If you're going through hell, keep going. ~Winston Churchill"

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                          • #14
                            Re: Exchange 2003 - Unable To Receive External Emails

                            Thanks guys... all seem to be working now since I changed my A Record's IP address to my static IP.

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                            • #15
                              Re: Exchange 2003 - Unable To Receive External Emails

                              Glad you got it sorted.

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