In a Ex2010/2013 coexistence scenario, and you configure an Ex2010 Edge server to route inbound and outbound SMTP traffic, how does the Ex2013 mailbox server route emails to mailboxes that are still on Ex2010 mailboxes?

Hello,

When there is an exchange 2010 edge transport server, internet mail flow occurs between the Transport service on the Mailbox server and the Edge Transport server, which effectively bypasses the Exchange 2013 Client Access server.

So far, we only refer to some technet articles and some blogs, but there is no detailed information for mail flow between exchange 2010 and exchange 2013 in these articles and blogs.

Based on my known, if messages need to go from an exchange 2013 mailbox to an exchange 2010 mailbox, they are picked up by the exchange 2013 transport service on Mailbox Server, and then sent to the exchange 2010 HUB Server using SMTP, and from there delivered into the Exchange 2010 Mailbox.

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