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Hello. Please help me figure out the problem.
We have a hybrid environment that includes an on-premise server MS Exchenge 2016.
There is a distribution group. Users are added to it.
All users except one receive emails sent to this distribution group.
When sending a letter from MS Outlook, when you select a distribution group in the "To" field, after expanding the group to check recipients, the user is not displayed in the list.
In this case, the user is a member of the group, this can be viewed through ADUC, ECP, Exchenge online, powershell cmd.
Initially, everything worked. The problem started after the user was mistakenly disconnected as fired. With the help of the PS script, the user's password and group membership are reset, the cloud mailbox (we have a hybrid) is transferred to shared for temporary storage, and the account is disabled.
The administrator's mistake was noticed immediately. The user account was activated, the mailbox was converted back, the group membership was returned.
Actually, after that, according to my observations, the user stopped receiving letters sent to the mailing group. What could be the reason?
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It looks like the answers on this thread were deleted for some reason. Are you still facing this issue?
It might take some time for Outlook to update its recipient cache, and you can also try removing/re-adding the user as member of the group. Once you do that, wait for a hour or so, and test via OWA. If he's still not getting any messages, run a message trace.
Hello! Enough time has passed for the scheduled update of the address book, more than a day.
I checked, indeed, when sending a letter from OVA, the user is present when expanding the distribution group.
When a group is expanded in the To field in MS Outlook, the user is not displayed among the members of the distribution group.
Keep in mind that in Exchange Online, OAB generation happens once every 24h, so it can take up to 48h for the updates to be reflected in Outlook. If the user is already visible in OWA, it's just a matter of time. Mail flow should be working correctly in Outlook too, as long as you don't expand the group (until it gets updated).
Hello. The reason is clearly not synchronization. I've tried adding new members to the group. In order not to wait for a long time, I updated the address books on the on-premium mail server, downloaded the updated address book on the client pc. As a result, new members are displayed when the distribution group is expanded in the To field, and this problematic user is not displayed.
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Hi @Andrey
If creating a new distribution group and add the affected user to it, would the user also not shown as a member?
Yes, I also checked this option. Created a new distribution group and included users. The problem user does not appear when expanding the group.
Thanks for the information.
Please consider opening a support ticket with M365 support so that they can take a deep look into this issue.
You can contact them by opening a new service request in Microsoft 365 admin center:
@Andrey check this user is hidden from address list. you can check it from admin center > users> effected user>mail> Show in addresslist > Yes