Can't add remote shared mailbox by using ECP into distribution group in Exchange Server 2019 and 2016 hybrid environment

Applies to: Exchange Server 2019Exchange Server 2016

Symptoms


In a Microsoft Exchange Server 2019 or Exchange Server 2016 hybrid environment, you use Exchange admin center (EAC) to add users into a distribution group. Additionally, into the other tabs inherent in a distribution group. However, if the user that needs to be added is a remote shared mailbox, the mailbox is not even available in the picker to be added. The same works fine when executed from Exchange Management Shell (EMS).

Resolution


To fix this issue, install one of the following updates:
For Exchange Server 2019, install the Cumulative Update 5 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019.​
For Exchange Server 2016, install the Cumulative Update 16 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.

References


Learn about the terminology that Microsoft uses to describe software updates.