Mail flow in a 2013/2010 coexistence


  • Hi all,

    We are in the middle of a 2010 to 2013 migration. I am trying to understand the mail flow before I decommission one of the 2010 server.


    root domain:

    child domain:

    Prior to migrating users from child domain to root domain, we are migrating users from exchange 2010 server in the child domain ( to new exchange 2013 servers in root domain (exch01 and All mailboxes have been migrated to new servers. and edge servers are to stay until we migrate to Office 365.

    All roles are shown in diagram below. So is required for inbound mail from external? There is no mailbox on it and it is clear from any relay (e.g. printers and scanners). Mail flows are shown in diagram,

    1) as outbound

    2) as inbound.

    Based on email header analysis, sometime inbound mails are going through and other times are not. Is anyone able to explain?



    Tuesday, November 8, 2016 6:13 AM

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