Microsoft Exchange Online will limit each organization to 3,000 dynamic distribution groups (DDGs) starting November 2025. Find the Exchange Online limits for various service areas, including address book limits, mailbox storage limits, and reporting and message trace limits, to name just a few. Few tenants might be affected, but the question might be asked why Microsoft is limiting DDGs at this point. This change is automatic and cannot be turned off. Adjust limits for individual mailboxes or all new mailboxes via mailbox plans.