Microsoft Office Tutorials and References
In Depth Information
Changing an MX record
For outbound messages, emails sent from Exchange Online mailboxes to external recipients
will be routed through FOPE or EOP. Emails sent from Exchange on-premises mailboxes for
external recipients will be routed directly to the recipients.
Centralized mail transport enabled
With centralized mail transport enabled, inbound emails will still be received by FOPE or
EOP first because of the change in MX records. Figure 11-93 depicts mail handling when
centralized mail transport is enabled:
1. An email is sent to two recipients, John and Eiji. The email is first received by FOPE or
EOP because the MX record has been changed accordingly.
2. FOPE or EOP scans the email for spam, virus, and other threats.
3. The email is sent by FOPE or EOP to Exchange on-premises.
4. Exchange on-premises receives the email and determines that Eiji’s mailbox is
on-premises and John’s mailbox is in Exchange Online.
5. Exchange on-premises makes a copy of the email and sends one copy to Eiji’s
mailbox on-premises and routes the other copy, addressed for John, back to FOPE or
6. FOPE or EOP receives the message from Exchange on-premises and recognizes that it
is destined for John, whose mailbox resides in Exchange Online.
7. FOPE or EOP delivers the email to John through Exchange Online.