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Adding new DAG to Exchange 2013 Hybrid Configuration has mailflow issues

    Question

  • We currently have a 6 physical server Exchange 2013 CU19 DAG and are attempting to move onto a newly created 2 virtual server Exchange 2013 CU19 DAG.  Everything seems to be ok but when I test mail flow as is from a mailbox on the new DAG the emails are all having to go through the servers in the old DAG to be sent to O365 which is understandable as they have not been added to connectors, etc.

    I assume to get these new servers configured correctly for Hybrid Config. all I would have to do is run the Hybrid Configuration Wizard selecting the two new servers and the wizard would do all that is necessary for me?

    I attempted this today but seemed to have a number of emails that seemed to be getting stuck in the queues yet there were some emails getting delivered. 

    Is there something I am missing with regard to mail flow for the hybrid config? 

    Those emails that were being delivered still seemed to be going through the old DAG servers (checking headers) to be sent to O365/external.

    Is this expected?  Is there anyway to test the new DAG mail flow on it's own?

    Once the few on-prem mailboxes (99% are in O365) have been migrated to the new DAG these old servers will be decommissioned so we need everything to be working through these new servers.

    Thanks in advance for any help/advice you may be able to give.

    Peter

    Tuesday, January 16, 2018 3:32 PM

Answers

  • I would test whether mail can actually get out of the new servers and that it isn't being blocked by a firewall or some such.

    Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
    Celebrating 20 years of providing Exchange peer support!

    • Marked as answer by PJD1906 Thursday, February 1, 2018 10:17 AM
    Wednesday, January 17, 2018 4:30 AM
    Moderator

All replies

  • I would test whether mail can actually get out of the new servers and that it isn't being blocked by a firewall or some such.

    Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
    Celebrating 20 years of providing Exchange peer support!

    • Marked as answer by PJD1906 Thursday, February 1, 2018 10:17 AM
    Wednesday, January 17, 2018 4:30 AM
    Moderator
  • Hi,

    Thanks for contracting our forum.

    Nothing missing, we need to setup connectors with running HCW. After run HCW we just need send testing emails from the two servers.

    And also check if any error message in the queue with the queued messages with the command below:

    Get-queue | fl name, *last*

    Hope it helps.

    Regards,

    Jason Chao


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    Wednesday, January 17, 2018 6:19 AM
    Moderator
  • Thanks for the suggestion.  Just trying to check with a colleague to find out if we have anything in firewall rules that could be affecting mail flow.
    Wednesday, January 17, 2018 11:21 AM
  • Thanks, please keep updating!

    Regards,

    Jason Chao


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    Thursday, January 18, 2018 1:08 AM
    Moderator
  • It appears our Exchange servers were in a firewall rule to allow traffic to O365.  Got the two new Exchange servers added to this rule and re-ran the Hybrid Configuration Wizard to add the two new servers back in to the Hybrid Configuration and monitoring the queues so far show no emails getting stuck. So that seems to have resolved that issue.  

    On a side note I am still a little concerned that the hops the emails are taking.  I currently only have one mailbox in a database on one of the new servers and it seems to route through the other new exchange server and then to one of the old physical servers and then to O365 as shown in the following header breakdown.

    EXC001 - new virtual Exchange server with active database mounted containing mailbox.

    EXC002 - new virtual Exchange server.

    EX02 - old physical Exchange server.

    OAB - secure link to O365.

    I need to be sure that email will still be routed to O365 once the physical servers are decommissioned.  Is there any way to test email routing would work without the physical servers prior to them being decommissioned to ease my mind?


    • Edited by PJD1906 Thursday, January 25, 2018 2:03 PM reworded
    • Proposed as answer by Jason.ChaoModerator Wednesday, January 31, 2018 9:38 AM
    Tuesday, January 23, 2018 9:15 AM
  • Glad to hear that the issue has been resolved!

    For your questions, we can add the newly added servers to the source server of the send connector and have a test.

    We can also setup a new send connector with only the newly added server and send test messages.

    Hope it helps.


    Best Regards,
    Jason Chao


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.


    Click here to learn more. Visit the dedicated forum to share, explore and talk to experts about Microsoft Teams.

    Wednesday, January 31, 2018 9:38 AM
    Moderator