Microsoft 365 mail roundtrip

Using contacts is the easiest way to setup the mail roundtrip in Microsoft 365.

It is also possible to use a mailbox instated of a contact for receiving email and setup a forwarding rule on the mailbox. This requires you however tot turn off allow external forwarding which is not a Microsoft best practice.

Create two contacts

1. Open the Microsoft 365 admin center
2. Open the users menu and then select contacts
3. Click add contact to create a mailroundtrip contact for receiving emails
   1. Set Display name to: mailrountrip-receive
   2. Set Email to: mailrountrip-receive@365.test-technolgy.nl
   3. Enable: Hide from my organization's global address list
4. Click add contact again to create the mailroundtrip contact forward to account
   1. Set Display name to: mailrountrip-infrasonar
   2. Set Email to: mail@mrt.infrasonar.com
   3. Enable: Hide from my organization's global address list

Setup rules

1. Open the Exchange admin center
2. Open the Mail flow menu and then select rules
3. Click the Add rule button and select Create a new rule
4. Name: InfraSonar mailroundtrip
5. Apply this rule if: Select The recipient and then is this person
6. Select the mailrountrip-receive contact you created before
7. Do the following: Redirect the message to these recipients
8. Select the mailrountrip-infrasonar contact you created before
9. Click Next
10. Leave the rule settings
11. Review and Finish
12. Ensure the rule is enabled!