How do I fix a dynamic distro that is missing one user

Question

I have 1 user not getting emails sent to the dynamic distribution group (DDG) for her OU. Everybody else in that OU gets the emails. I used the Get-Recipient command to show everybody in that DDG, and sure enough she is not showing up.

Info I found online indicates she could be just "mailbox" so I tried to fix the filters. I used this command to "fix" the filters:

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

After that I listed the filters for this DDG, and it did update it to include UserMailbox, MailUser and and MailContact. I listed filters for a DDG I have not updated, and other than not having the new settings, the filters look the same (in other words I didn't accidentally remove or change anything).

Fixed the filters nearly 24 hours ago, user still does not show up in the DDG.

What am I missing?

Answer 1

Hi @Mike P. Smith,

Welcome to the Microsoft Q&A platform!

Based on your description, you have taken the correct steps to update the filter for the dynamic distribution group (DDG). Here are some other things you may want to check:

1. Sometimes, the membership list may not be updated immediately. You can force a refresh of the DDG membership list using the following command:

Set-DynamicDistributionGroup -Identity sales@contoso.com -ForceMembershipRefresh 

This can help ensure that the changes take effect.

2. Verify that the user's properties match the filter you set. For example, make sure that the user is indeed UserMailbox, MailUser, or MailContact.
3. Use the Get-Recipient command with the **RecipientPreviewFilter**to see if the user appears in the results:

Get-Recipient -RecipientPreviewFilter (Get-DynamicDistributionGroup -Identity sales@contoso.com).RecipientFilter 

This can help you determine if the user meets the criteria defined by the filter.

4. Since you have a hybrid setup, make sure that users are syncing correctly between your on-premises Exchange and Exchange Online environments. Sometimes, synchronization issues can cause differences in group membership.
5. Make sure the user is not hidden from address lists. You can check this property using:

Get-Mailbox -Identity user@domain.com | Select-Object HiddenFromAddressListsEnabled 

If the user is hidden, they will not appear in the DDG.

6. Check the message tracking and logs to see if there are any errors or issues related to email delivery for the user.

If you have tried all of these steps and the problem persists, then look in detail at the specific properties and filters.

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Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.

Best,

Jake Zhang

Answer 2

And the answer is...

AD attribute mailNickname was blank. That causes some kind of sync issue with Exchange online. Once I set the user's mailNickname to her user ID, she started showing up in the Dynamic Distribution Group.

Now I'll work on finding other such users in my AD.

Thank you Jake, appreciate your help.

Answer 3

I am running a hybrid configuration, so my Dynamic Distribution Groups (DDG) are on-prem, which I believe is the only time you'll see this problem.

I have had some users, that for years have not been getting emails that are sent to our All Users DDG or their location DDG. Finally I heard about this one user that did not get the All User email regarding a company event that required an RSVP. Many days later, I have it fixed, and this was affecting more than just one user.

This all comes down to mailNickname in the Attributes of the user account. If that is <not set> the user will never be included in any DDG. If you get into the Properties for the user's account, while in the OU where that accounts resides, you will see the tab for Attribute Editor. You can edit mailNickname using the Attribute Editor. If you're not in the actual OU, this tab does not appear (IE: don't open from search results).

The mailNickname normally matches the SAMAccountName, but even when it doesn't match (like where somebody got married and changed their name), the user will receive emails sent to any DDG they are in.

The command below will show you which accounts have blank (<not set>) mailNicknames. Well, it will show you all users if you point high enough in your OU structure. For example, we have an OU called Mail, under that are several OUs which align with our various locations. To see all my users, I point to Mail. To check out just a sub OU, I would change the distinguished name to point to that OU.

Anyway, when the list scrolls up the screen, just scroll back and forth looking for blank mailNicknames. Any account that doesn't have an email account, or is not used in any DDGs, can be ignored. This will be in PowerShell, not Exchange PowerShell.

Get-ADUser -Filter * -SearchBase "<distinguished name> -Properties mailNickname, sAMAccountName | Select-Object sAMAccountName, mailNickname

You still have to change the filters on your DDG's because some user's have a different recipient type than what O365 will have. O365 sets all users to mail-enabled. Your on-prem AD can have UserMailbox, MailUser, and MailContact.

The following command will fix your filters. I got errors sometimes when I used the name of the DDG, while other times it worked. Using the email address for the DDG worked every time. This will be in Exchange PowerShell on your on-prem Exchange server.

Set-DynamicDistributionGroup -Identity <DDG's email address> -RecipientFilter {(RecipientType -eq 'UserMailbox') -or (RecipientType -eq 'MailUser') -or (RecipientType -eq 'MailContact')}

Not sure if somebody is being left out? If the mailNickname is blank, they are being left out. But you can list the members with the commands below. This will be in the Exchange PowerShell on your on-prem Exchange server:

• create a variable that contains the name of any DDG. I have a DDG for All Users, and one for each location. You have to re-run at least the last two commands to see if you have fixed a user. And of course if you re-run the first command you'll need to re-run that last two.

$dl2 = Get-DynamicDistributionGroup <DDG email address>

 * Build a 2nd variable for the last command to use.

$allr2 = Get-Recipient -RecipientPreviewFilter $dl2.RecipientFilter -OrganizationalUnit $dl2.RecipientContainer –ResultSize Unlimited

 * List all the members with whatever info you want, name, primary email, etc.

$allr2 | Select-Object Name,PrimarySmtpAddress,Title,Department,city

I came into this with very little experience. This community helped a lot, but at the end of the day I found the problem by opening two users in the same OU. One gets the emails and the other user doesn't. I compared every attribute side by side, and something as innocuous as mailNickname was causing this problem (@ Jake Zhang - thank you for suggesting I look in detail at the specific properties and filters). Microsoft uses this field when creating the list of users for the email you are sending with a DDG. There is a filter in Exchange Online that says this field can't be blank. Why? Who knows, but it cannot be blank. By default is it supposed to match the SAMAccountName, but this clearly does not always happen (again, I don't know why).