If you’d like to allow one of your colleagues to help you maintain the list, you can add them as a manager or an owner.
Owners have all the permissions that you do. You should have no more than one or two owners per group
Managers can add or remove users and always post to the group. However, they can’t delete the group or remove owners.
To add a manager, first add him or her as a member. Then, go into your “Manage members” area.
Check the box next to the person you’d like to make a manager. From the Actions menu, choose either Owner or Manager (as appropriate) from the “Add to role” menu.
To remove Manager or Owner access, check the box next to the person you’d like to remove and choose Actions -> Remove from role and the appropriate role.