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Office 365 Groups with additional Email Addresses and DBEB (internal Relay Domain / authoritative Domain)

Thorsten_S asked
Last Modified: 2017-05-09
I have a problem with a Office 365 Group. This Group has one primary E-Mail address (groupname1@contoso.com) and E-Mails can be send from external senders to this Group. When we add additional E-Mail addresses to this Office 365 Group (groupname2@contoso.com) and external senders are trying to send E-mails to that address it does not work.

When I go to Exchange Online Admin Center and change my accepted Mail Domain from "authoritative" to "internal relay" it is working. The additional E-Mail addresses are now working from extern. By doing this I deactivate DBEB (Directory Based Edge Blocking). DBEB is only active when my domain is "authoritative".
When I understand everything right, the additional E-Mail addresses are not synced to EOP (Exchange Online Protection) and because of that the E-Mails are unknown for my Maildomain and the mails to the additional E-Mail addresses are blocked.

Is there a solution for that problem?
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Hello Michev,
thanks for your quick reply. So when I understand it correct I have to configure every mail alias step by step as primary. After that procedure I can change the primary mail address back to the initial mail address and all alias addresses were synced to EOP and will remain there?
Most Valuable Expert 2015
Distinguished Expert 2019

Yup, and wait few minutes between the changes to give it a chance to sync.

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