Outlook Desktop App


Distribution list owner(s) can manage members via Address book in Outlook Desktop App. You can just open Address book and double click the Distribution List to modify the members.  


Note: Changes can take up to 8 hours to sync (between Outlook Desktop and Microsoft 365 or vice versa)



Outlook on the Web


Distribution list owner(s) can manage members by clicking the gear icon to open Settings > General > Distribution groups