Some users are missing from the synced Distribuiton groups/lists on Exchange Online

Question

Hi,

so, we are discovering that some random users who are a member of a certain distribution list on our Exchange on premise server (Exchange 2016) are missing from Exchange online synced Distribution groups.

we are currently in a hybrid set up and we moved all of our mailboxes to EXO months ago.

Example of our issue:

So, if I go to our "Sales" distributions group on our Exchange on-premises, I see that all of the members are present except maybe one or two. I can remove and re-add them, and it shows up on O365, I can add new users and they show up on Exchange Online Distribution list after the sync.

My question is:

Where should I start to troubleshoot this issue? What could have caused this issue?

Thanks in advance.

Answer 1

Hi @Sophia ,

According to my research, as long as the these missing members in the sync scope and not filtered out, they should sync just fine. Check the metaverse object properties. We can launch the configuration wizard for AAD Connect, When validating domain / ou filtering, it is observed that “sync selected domains and OUs” is the option.

Here's a troubleshooting guidance on Office 365: Troubleshooting distribution lists and distribution list memberships for your reference.
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

---

If an Answer is helpful, please click "Accept Answer" and upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 2

We found that missing members of a distribution list were hidden in GAL. Once this was unchecked and sync ran, members showed as expected.