I'm trying to grant full mailbox by security or distribution group to several mailboxes. Eventually I'd like to use the some idea with individual Calendars within our organization to grant reviewer (Read Only) access. This would be ideal verses having to granting each person individually. The problem is I've tried using a security group both global and universal and a distribution group and neither seem to work. When I run a get-mailboxpermission against the mailbox it shows the distribution group as having full mailbox access but no user in the group has the mailbox appearing in their outlook client nor can they access it by adding it as an additional mailbox to open as part of their profile settings.