How to manage groups with groups in Exchange 2010 - Exchange Team Blog

You\'ve migrated from Exchange 2003 to Exchange 2010. Your users are reporting that they\'re unable to modify distribution groups that they could in the past. In How to Manage Groups that I already own in Exchange 2010?, we showed you that in Exchange 2010, users had permissions to create new distribution groups and remove the distribution groups they owned.

This did help a few of your users but some are still unable to modify their distribution groups. You need to look into this...!

Issue:
When User1 tries to add a new member to the DistributionGroup1 distribution group, she gets this error:
Changes to the distribution group list membership could not be saved. You do not have sufficient permissions to perform this operation on this object!