New Limit for Dynamic Distribution Groups in Exchange Online

Dynamic Distribution Groups (DDGs) are mail-enabled groups used to send massive emails like announcements, and other information within a Microsoft 365 environment. It has dynamic membership capability where members have been changing automatically based on the configured conditions in the group. However, not all DDGs are used frequently in the organization and are left unused for a longer period. For efficient usage of DDGs, Microsoft has come up with a new limit for DDGs creation in a tenant.

Starting April 2025, every Microsoft 365 organization can create only up to 3000 DDGs. After the rollout, the limitation will be enforced on all tenants and admins can’t make any change. If admins want to create further, they need to delete the existing DDGs to create a new one after exceeding the limit. So, admins must review the DDGs usage periodically to stay within the limit. Let’s dive into how to find and delete unused DDGs in Exchange Online.

If your organization has exceeded the limit and you want to get a list of all DDGs to make a decision, follow the steps below.

• Sign in to Exchange Admin Center (EAC).
• Navigate to Reports –> Mail Flow –> Dynamic distribution group report.

In this report, you will find the used and unused dynamic distribution lists in your organization with details, such as group name, email, last used date, and the number of times the group was used. You can also export the list of dynamic distribution list to CSV using the Export option.

If you want to delete the unused dynamic distribution groups,

• Navigate to EAC –> Recipients –> Groups –> ‘Dynamic distribution list’ tab.
• Select a group that you want to delete.
• Click on ‘Delete group’ option on the top.

Note: You can’t delete multiple DDGs in EAC.

Apart from EAC, you can also use the PowerShell to find and delete unused DDGs in your organization.

Step 1: To find a list of all dynamic distribution group in Microsoft 365, you can use the ‘Get-DynamicDistributionGroup’ cmdlet.

Get-DynamicDistributionGroup –ResultSize Unlimited | Select Name, PrimarySMTPAddress, ManagedBy

Sample Output:

Step 2: After retrieving the DDGs, you can delete the unused DDGs using the below cmdlet.

Remove-DynamicDistributionGroup –Identity <GroupName> 

Also, you can efficiently export the list of all dynamic distribution lists along with their member details using the PowerShell script.

Highlights:

• You will get Dynamic Distribution Group – summary report and detailed members report as per your needs.
• You can export the results to CSV.
• Output can be filtered to list Empty group. I.e., DDL without members.

Apart from these, you can achieve more using the script and customize the output to fulfill your requirements.

Download Script: Get Dynamic Distribution Group Members

After retrieving the list of all DDGs in your organization, you can delete the unused groups using the PowerShell cmdlet or Exchange Admin Center.

I hope this blog helps you to efficiently fetch and delete the dynamic distribution lists and avoid exceeding the limit in your organization. Feel free to reach us through the comments section for any queries.