M365 Changelog: Feature update: Modern Dynamic Distribution Groups

MC340293 – Updated April 14, 2022: Microsoft has updated the content below to show as intended. Thank you for your patience.

Microsoft is modernizing Dynamic Distribution Groups (DDGs) to bring you a more reliable, more predictable, and better performing experience. We’re making changes that will reduce mail delivery latency, improve service reliability, and allow you to see the members of a DDG. This rollout will provide the functionality to all Exchange Online organizations.

When this will happen:

Microsoft will begin rolling this out in early April and expect to complete by late April (previously mid-April).

How this will affect your organization:

Today, the membership list for a Dynamic Distribution Group is calculated every time a message is sent to the group, based on filters and conditions that you have defined for that group. Since these filters can be highly complex, it can take a long time to calculate the recipient list, leading to delayed mail and in extreme cases, reliability issues. In addition to this, as DDGs are resolved only upon being sent, the actual recipient list is unknown to the sender, which can present potential compliance issues for our customers.

New changes:

  • Instead of calculating group membership in real time, Microsoft will be storing the membership list for each Dynamic Distribution Group. This membership list will then get updated periodically once every 24 hours.
    • Note: When you create a new Dynamic Distribution Group or modify the filters of a group, it may take up to 2 hours until your group is ready to be used for the first time after creating or modifying the group filters.


  • With this update, you will be certain of the recipient list of a Dynamic Distribution Group prior to a message being sent, which will help address any potential compliance concerns. You will have the capability to view Dynamic Distribution Group members via the Get-DynamicDistributionGroupMember cmdlet. For more information, please visit Get-DynamicDistributionGroupMember. In addition, by storing the calculated list of members on the Dynamic Distribution Group object, Microsoft will deliver messages more quickly and our service will have improved reliability.

What you need to do to prepare:

You don’t need to do anything since the functionality of Dynamic Distribution Groups remains the same. However, you may consider updating your user training, and notifying your helpdesk as there are behavioral changes involved. Since the membership list is no longer calculated each time, a message is sent, the recipient list may not always be up to date as it gets refreshed every 24 hours.

Additional information