Users can't add and remove members from the distribution lists they manage on Exchange 2010
When a user try to add or remove a user from a distribution group they manage/own, they get the following error message:
"Changes to the distribution list membership cannot be saved. You do not have sufficient permission to perform this operation on this object."
This behaviour is by design on Exchange 2010.
You can change this behaviour by using the Manage-Groupmanagmeentrole.ps1 script: http://msexchangeteam.com/files/12/attachments/entry453244.aspx
Microsoft Exchange 2010