Last week, the Exchange development team announced two interesting developments. Stopping duplicate dynamic distribution groups and cross-tenant message recall. Preventing tenants from creating duplicate DDLs saves service resources and might make tenants easier to manage. The real value is in cross-tenant message recall, which solves a problem by allowing users to recall messages delivered outside their tenant. The facility only works if the receiving tenant allows, but nothing can be done for messages delivered outside Microsoft 365.
Exchange Online is imposing a new tenant-wide limit of 3,000 Dynamic Distribution Groups. Few tenants might be affected, but the question might be asked why Microsoft is limiting DDGs at this point. Is it a cunning plan to prompt people to use dynamic Microsoft 365 groups instead? Or are some tenants abusing DDGs in weird and wonderful ways? Who knows, but the limit applies from early April 2025.
It seems like it should be possible to transfer a membership rule from an Exchange dynamic distribution list to a dynamic Microsoft 365 group/team, but it’s not. Different directories, schemas, properties. and syntax conspire to stop easy conversion. It’s a pity, but that’s the way life and technology sometimes go…
This article explains how to create a new Microsoft 365 group and team using the membership and properties of an Exchange Online dynamic distribution list. The process is reasonably straightforward, but as always with PowerShell, there are some interesting turns and twists that must be navigated en route.
Microsoft is changing the way the Exchange Online transport service resolves the membership of dynamic distribution groups. Instead of doing this when someone sends a message to a dynamic group, Exchange resolves the membership once daily and whenever the recipient filter changes. It’s a reasonable approach designed to make messages move faster and more reliably, and it’s similar to the way that Azure AD dynamic groups maintain their memberships, so it shouldn’t make much difference.
