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Email sent from a user on Server A destined for a user on server B is bouncing.

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  • Email sent from a user on Server A destined for a user on server B is bouncing.

    Hi Guys / Gals,

    I will try to be as clear as possible with this so you hopefully wont have to ask too many obvious questions to get to the root of this problem.


    Server A - SBS 2008 with email domain name - (obviously not the real name)
    Server B - SBS 2003 with email domain name - (obviously not the real name)
    Both servers download email via POP from a third party mail provider.
    The servers are in different geographical locations but they both share the same email domain name, ( its a long story........
    The companies are seperate but do need to communicate regularly with each other via email.

    Current situation:

    Server A was migrated from SBS2003 to SBS2008. Everything is working perfectly except for one thing which was working fine before. Email sent from a user on Server A destined for a user on server B is bounced back to the sender on server A.

    The problem occurs when a user on SBS2008 ([email protected]***.com) tries to send an email to an external user that has the same email domain name. ([email protected]***.com) On the SBS2008 server, Exchange 2007 traps the email as it is authoritative for the domain and as it rightly cannot find Sarah as an AD user, it sends an NDR back to the sender.

    This also happened a few years ago when both servers were originally set up but the fix was simple, a tick in the "Forward all unresolved messages to host" fixed it. However, there is no similar option in Exchange 2007 that I can find.

    If there is a step by step fix for this I would appreciate it as the users are starting to get nasty.

    Thanks in advance.

    Last edited by Wired; 1st December 2009, 22:00. Reason: nixed emails

  • #2
    Re: Gold star for whoever can answer this!

    consider using a routing group ? I'm not 100% sure if this will acheive your aim.. but my understanding is it can 'route' rather than 'transport' the mail to the other server..

    I'm not sure how that would go with SBS however..

    It's not a step by step answer, but it's a nudge in what I suspect the direction could be..
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    • #3
      Re: Gold star for whoever can answer this!

      Thanks tehcamel for your post. Had a play with routing groups but they would not resolve the issue or offer me a way round it. However I did discover the solution thanks to Enda Flynn from Microsoft who sent me a link to a Microsoft technet blog.

      In case anyone else has this issue, the details are below in the hope that they may be of help to another SBS2008 installer.

      The "accepted Domains" section of the Exchange 2007 management console says an Internal relay domain is for relaying email to another AD forest within the organisation so I excluded this from my initial consideration as I needed the email to be sent to a mailserver outside of the exchange domain. (eg This description is not complete/accurate as you will see below from the description taken from the Technet article.

      The document on the Microsoft Technet blogging site states the following:

      Internal Relay Exchange accepts email for this domain, but is not the authority for all of its mail delivery, meaning that some recipients in this domain do not have mailboxes in the Exchange Organization. Through the use of an Internal Relay Accepted Domain, email for any unresolved recipients will be routed through the existing SMTP send connector.

      If the console had stated that, it would have saved me hours of searching the web. That was exactly what I needed to do and I have done tests and all is now working as before.




      • #4
        Re: Gold star for whoever can answer this!

        Consider using a meaningful title please
        Reported for change

        These links may help you out:
        Last edited by Ossian; 3rd December 2009, 11:39.
        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

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