In Microsoft Exchange Server 2010, users can create and manage distribution groups and distribution group membership. These users are delegated ownership of the group by the ManagedBy property. The default owner of a distribution group is the user or administrator who creates the group. However, you can use the EMC or the Shell to change the ownership of a distribution group.
This example replaces the current owner of the distribution group Managers with the new owner email@example.com
Set-DistributionGroup -Identity Managers -ManagedBy firstname.lastname@example.org