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Hybrid migration Exchange 2007 on-prem

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Hello All


I will be performing a hybrid migration from on-prem 2007 sp3 to O365. The current A record for autodiscover, OWA, and OA all point to the 2007 CAS server ( When I introduce the 2010 hybrid server do i need to chang DNS to point and to the 2010 hybrid server, or do i keep pointing and to the 2007 CAS server?  I'm assuming i need to introduce a new namespace for the 2010 hybrid server, but i am not sure what purpose doing so porvides?


As you can see i am a bit lost on this coegisistence piece


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  • Hi skipster,

    I understand that you are performing a hybrid migration.
    There is an article which provide helpful information.

    Larry He

    0 out of 1 people found this post helpful.

  • Thank you Larry for the providing the link, it was helpfule.

    When i go through the Exchange Server Deployment Wizard for a Hybrid migration the task "Redirect Outlook web connections to Hybrid server" suggest's that i need to create a new namespace for the hybrid server i.e, and continue pointing "" to the 2007 CAS server. The instructions in this step suggest that all usrs will hit "" (Hybrid server) and the Hybrid server will redirect the request to either the 2007 ( or provide a link to OWA in O365.

    If i follow these directions then my users have to learn a new name for OWA access (OWA.Contoso). However if i pointed to the Hybrid server , and then configured the externalurl on the 2007 CAS Server to, and pointed to the 2007 CAS server, then users do not have to learn a new url for OWA access. Its almost like the Exchange Server Deployment wizard has it backwards? Again if i followed the wizards steps i see two things breaking until the clients are reconfigured

    #1 Outlook Anywhere. The outlook client requires that the principal name in the cert match the name thats configured in the  proxy settings in the outlook client. If is the principal name then this is going to break already configured Outook anywhere clients.

    #2 My users will have to be given directions on how to access thee mailbox using OWA, as they have never used

  • Hi skipster,


    We can configure the cloud-based Outlook Web Application redirect during the Hybrid migration so that your user could still use the old URL for OWA, please refer the below link for detailed information:

    Configure Outlook Web App for an Exchange 2010 Hybrid Deployment


    In addition, for specific deployment guidance of Hybrid Deployment, please refer the below link, and you can choose different scenario as your demands:



  • Hi skipster,


    Is these information provied by JQQ helpful?
    Do you have any other questions?

    Larry He