Hi.
We are currently migrating from Exchange 2007 to Exchange 2013. We have Exchange servers across 3 AD Site (A, B &C). Right now, all our users are on Exchange 2007 except 2-3 test users. Exchange 2013 was installed in site A without any issue. At that moment, mail flow between users from site A to site B keep using Exchange 2007 hub servers in both directions; Exchange 2013 Transport Servers in site A were not used at all.
When we installed Exchange 2013 in site B, mailbox flow between Exchange 2007 users from site A to Exchange 2007 users in site B start using site B Exchange 2013 Transport servers. Why?
Right now, when site A users are sending email to site B, it’s using site B Exchange 2013 Transport Servers (Site A 2007 Mailbox Server, Site A 2007 Hub Server, Site B Exchange 2013 Transport Server, Site B 2007 Hub Server, Site b 2007 Mailbox Server). When site B users are sending email to site A, it’s keep using Exchange 2007 hub. (Site B 2007 Mailbox Server, Site B 2007 Hub, Site A 2007 Hub, Mailbox, Site A 2007 Mailbox Server).
Can someone explain why Exchange 2013 transport services are only used in site B and not A? Any documentation I can read that explain the result?
Thank you.