How to migrate all distribution groups to Microsoft Office 365?
2. manual instructions
Create an export of the members and properties of your distribution group to be migrated
Delete the current distribution group on-premises
Recreate this group in Office 365 Online .
Add an owner/manager.
3. Management of end-user distribution groups.
The migration of the group(s) to Office 365 allows you to add owners or several to the properties of this group.
This setup is perfect if you want to delegate management.
Click on groups
You can see here the groups to which you belong.
Open the group and add the desired members or groups.