SBS 2003 to SBS 2008 Migration SMTP Inbound Not Working

Posted on 2010-01-01
Last Modified: 2013-11-30
I am trying to finish a sbs 2003 to sbs 2008 migration and have run into an issue. I cannot get external inbound mail to work. Outbound mail is working and as long as I have the 2003 box up and running inbound mail works. But when I disconnect the 2003 box from the network inbound mail stops. I can telnet to both boxes from inside the network on port 25. The 2003 box responds with the external domain name ( and the 2008 box responds with its local FQDN (server.domain.local). The 2003 box will respond to telnet on the outside network. The firewall is set to NAT the external address to either internal server. I don't know how to make 2008 except the inbound mail.

Thanks in advance
Question by:Carter_Machinery
    LVL 77

    Expert Comment

    by:Rob Williams
    2008 defaults to Have you either changed this or set up a new DNS host record with the service provider that manages your external DNS?
    LVL 38

    Expert Comment

    by:Philip Elder
    Please have a look at our migration guide and follow through to where a step may have been missed:

    LVL 76

    Accepted Solution

    Your firewall needs to forward TCP port 25 traffic to the SBS 2008 box and you need to remove the internal connector between the SBS 2003 box and the SBS 2008 box.
    This should allow the SBS 2008 box to receive mail.

    Author Closing Comment

    Thank you very much for the advice. I had port 25 forwarded to both boxes which was apparently causing issues. Removed the 2003 box, made sure 2008 was defined as and it is working now.

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