Microsoft to Restrict Dynamic Distribution Groups in Exchange Online
Microsoft will enforce a new dynamic distribution group (DDG) limit in Exchange Online.
Published: Mar 11, 2025
Key Takeaways:
- Microsoft is enforcing a 3,000 dynamic distribution group (DDG) limit for Exchange Online tenants.
- IT admins won’t be able to disable this restriction.
- Microsoft encourages organizations to review and remove inactive DDGs.
Microsoft is implementing a new tenant-wide cap of 3,000 dynamic distribution groups (DDGs) for Exchange Online customers. Starting next month, organizations hitting this limit must delete existing DDGs before creating new ones.
In Exchange Online, dynamic distribution groups (DDGs) are special types of mail-enabled groups that automatically update their membership based on specific criteria. Unlike static distribution groups, which have a fixed list of members, DDGs dynamically adjust who is included each time an email is sent to the group. Administrators can create and manage DDG through the Exchange Admin Center or using PowerShell commands.
Microsoft is enforcing this new dynamic distribution group (DDG) limit to enhance efficiency and streamline management in Exchange Online. The company aims to optimize resource usage by encouraging organizations to review and remove unused DDGs.
Microsoft confirms that this new setting will be enabled by default, and IT admins won’t have the option to disable it for end users. However, organizations with fewer than 3,000 DDGs will not be affected.
How to check for inactive dynamic distribution groups in Exchange Online
Microsoft plans to begin enforcing this new limit in early April 2025. The company recommends administrators to regularly check for inactive dynamic distribution groups. The Exchange Admin Center (EAC) provides a report that shows how many DDGs an organization has and provides insights into their usage.
Administrators will be able to access this report by navigating to the EAC > Reports > Mail flow > Dynamic distribution group report. They will be able to filter the data based on different time periods such as 7 days, 30 days, 90 days, and a custom start date (within the last 80 days). These options should help IT admins analyze the usage patterns of DDGs over different time frames.
Last month, Microsoft announced plans to change the tenant-wide outbound limits for Exchange Online in the coming months. The new rate limit will be based on the number of email licenses administrators have within their tenants.