no mailflow from Exchange 2010 to Exchange 2003 during coexistance.


  • Hi All,

    We have a single Exchange 2003 server up until this weekend.  We'd installed a new Exchange 2010 server with co-existance in mind.  After a successful installation, we're faced with the problem that there is no mailflow from 2010 to 2003.  I've created a user with a 2010 mailbox for this test.  No 2003 users have been migrated to 2010.

    1.  Emails from 2010 user is unable to send to external recipient (stuck in queue).
    2.  Emails from 2010 user is unable to send to 2003 reicipient (stuck in queue).
    3.  Emails from 2003 users to 2010 user successful.
    4.  Emails from external sender to 2010 user successful.

    I have removed and recreated the Routing Group Connector according to Microsoft and the results are the same.  It's bi-directional for the RGC.

    We have a BES and I have checked these instructions and applied them and results are still the same.


    Can someone shed some light?


    • Edited by czhmious Tuesday, February 14, 2012 11:59 PM
    Tuesday, February 14, 2012 11:58 PM

All replies

  • What error is the queue showing?  Have you recreated the routing group connector?  How is it configured?  Run Get-RoutingGroupConnector | FL and post the results here, please.

    Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

    Wednesday, February 15, 2012 3:30 AM
  • The queue viewer shows Next Hope Domain as cn-first routing group, cn=routinggroups,.......

    Delivery type: SmtpRelayToTiRg

    Status:  Retry

    Message Count:  5

    Last Error:  451 4.4.0 DNS query failed.  The error was:  SMTPSEND.DNS.NonExistentDomain; nonexistent domain

    Wednesday, February 15, 2012 3:37 AM
  • Please Refer these Links and update us ,



    Verify this settings as well

    Satheshwaran Manoharan | Exchange 2003/2007/2010 | Blog:http://www.careexchange.in | Please mark it as an answer if it really helps you

    Wednesday, February 15, 2012 5:18 PM
  • Follow Satheshwaran's suggestion to check the DNS settings.

    Mostly this may issue for the DNS server, can you resolve the Exchange 2003 on Exchange 2010?



    Evan Liu

    TechNet Community Support

    Thursday, February 16, 2012 8:29 AM
  • I'm also currious how your routing group connector looks like, please post the result here

    And here's one more additional link you can read regarding the upgrade of Transport from 2003 to 2010


    Make sure that it's open between the servers (firewall openings) and that the connectors is working

    Check smtp logs and queue logs and post the errors in here

    Jonas Andersson | Microsoft Community Contributor Award 2011 | MCITP: EMA 2007/2010 | Blog: http://www.testlabs.se/blog | Follow me on twitter: jonand82

    Thursday, February 16, 2012 4:57 PM
  • DNS is fine, create a send connector on Exchange 2010 or an SMTP connector on Exchange 2003 to send emails to Internet.

    This issue occurs when Exchange 2003 was configured to use the SMTP virtual server to send emails to internet and then Exchange 2010 is introduced in the environment.

    We should not have any smarthost configured on SMTP VS on exchange 2003, if it is using any then put it on SMTP connector or Send connector.

    Exchange Solutions

    Friday, February 24, 2012 8:50 AM
  • Any Updates on this issue ?

    Satheshwaran Manoharan | Exchange 2003/2007/2010 | Blog:http://www.careexchange.in | Please mark it as an answer if it really helps you

    Monday, February 27, 2012 3:53 PM