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Distribution list never updates

Mitchell Carroll 0 Reputation points
2026-02-02T19:54:31.76+00:00

I manage some distributions lists on Exchange Online Admin portal. I have updated one over a week now and users are still showing the old users in the list and none of the new ones. This happens on BOTH the web app of Outlook and the desktop app. However if you do not expand the list to the members and just send it, it sends to the correct users and not what is shown in the members list on Outlook.

This is making users continuously submit tickets with our IT team to update the list even though it has already been updated. Other users have been expanding the list and thus sending it to the wrong users.

Anyone have any ideas why this is happening?

Outlook | Web | Outlook on the web for business | Contacts
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  1. Jeanie H 11,910 Reputation points Microsoft External Staff Moderator
    2026-02-03T01:38:10.9466667+00:00

    Dear @Mitchell Carroll, 

    Thank you for posting your question in the Microsoft Q&A forum.  

    Based on what I have observed, this is a server-side issue in Exchange Online and it impacts multiple users (both Outlook on the web and Outlook desktop), rather than being an isolated issue affecting a single account. As a result, this issue cannot be fully troubleshot at a general level within the forum. As I am also a moderator, I have the same experience as you and other users. Moderators and contributors, including external Microsoft employees in this forum, cannot directly intervene in Microsoft product features or access back-end systems. Our role is limited to providing technical guidance on reported issues, requests, or ideas.  

    To allow Microsoft to investigate this further, I kindly ask that you reach out to the Global Administrator of your tenant and request them to submit a support ticket directly with Microsoft.

    Once the ticket is created, Microsoft Technical Support will review the case and route it to the Exchange Product Team for deeper backend investigation. 

    Below, I will include guidance outlining the steps to create the support ticket. Please help me follow these steps accordingly. 

    • Go to the admin center at https://admin.cloud.microsoft 
    • On the bottom right side of the page, select Help & support. 
    • Type a question or keyword into the text box. If you get a drop-down list, select the one closest to your question, or continue typing your question, then press Enter. 
    • If the results don't help, at the bottom, select Contact Support. 
    • Enter a description of your issue, confirm your contact number and email address, select your preferred contact method, and then select Contact me. The expected wait time is indicated in the Contact support pane. 

    While Microsoft is investigating, to avoid emails being sent to incorrect recipients and to prevent any work disruption, please help me do not expand the Distribution List in Outlook.

    If you need any additional information or assistance while submitting the ticket, please feel free to reach out. 

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  2. Q&A Assist
    2026-02-02T19:54:41.71+00:00
    AI generated content. This question contains an answer created with AI from Q&A Assist. Learn more

    It sounds like you are experiencing issues with the membership updates of your distribution lists in Exchange Online. Here are a few potential reasons and solutions for why the distribution list may not be reflecting the most current members:

    1. Propagation Delay: After making changes to a distribution list, it can take some time for those changes to propagate throughout the system. Typically, it may take up to 60 minutes for distribution groups to be fully created and ready for management. If you've made changes recently, ensure that enough time has passed.
    2. Dynamic Distribution Groups: If you are using a dynamic distribution group (DDG), the membership list is calculated based on specific rules. If you modified the membership rules recently, the old membership list may be cleared out, and the new list might still be processing. You can check when the DDG was last refreshed in the Exchange admin center or by using PowerShell commands.
    3. Membership Rules: Ensure that the membership rules or filters defined for the DDG are correct. If no recipients match the rules, the group will show no members. You may need to review and adjust these rules if necessary.
    4. Force Membership Refresh: If the membership list isn't updating as expected, you can force a refresh using Exchange Online PowerShell. This can be done with the command Set-DynamicDistributionGroup -Identity <DDGIdentity> -ForceMembershipRefresh, but ensure that more than one hour has passed since the last refresh.
    5. MailTip Issues: Sometimes, MailTips may display incorrect information regarding the size of the group. This can lead to confusion among users. The Exchange Engineering team is aware of this issue and is working on a solution.

    If the problem persists, consider reaching out to Microsoft support for further assistance.

    References:

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