Dynamic Distribution List member's name showing as Object ID - unable to receive emails.

Question

We have a dynamic distribution list, (DDL) when running Get-DynamicDistributionGroupMember -Identity "NAME" for the list it shows one of the member's names as an Object ID rather than their display name.

This user is unable to receive emails sent to the distribution list.

I have removed the value which is adding the user into the DDL, forced membership refresh to see the user is no longer a member and then re-added the value to re-add the member. They still show as an Object ID.

I have also removed and re-added their exchange online license in between the step above.

Other context:
We are a hybrid environment with AD only, the user is relatively new.
I also posted my question here and was advised to post on this forum.

Answer 1

Hi @Lily Joyce ,

This problem occurs if the dynamic distribution group was set up before the environment became a hybrid deployment and if the dynamic distribution group uses filters to include only mailboxes. Mailboxes that are migrated to Microsoft 365 become mail-enabled users in the on-premises directory.

Use the Set-DynamicDistributionGroup cmdlet to update the filters for the dynamic distribution group to include mail-enabled users. For example, run the following command:

Set-DynamicDistributionGroup -Identity sales@contoso.com -RecipientFilter {(RecipientType -eq 'UserMailbox') -or (RecipientType -eq 'MailUser') -or (RecipientType -eq 'MailContact')}

Refer to: https://learn.microsoft.com/en-us/exchange/troubleshoot/groups-and-distribution-lists/dynamic-distribution-group-members-not-receive-emails

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