We have Exchange 2010. We are migrating some users from our mail servers to another company. A vendor tried to take 300 mailboxes and using a script add a Service account needed to the Full access permission via the Shell in EMC. The cmd is below and repeats for all 300 mailboxes. It seems to run successfully but when you open the EMC GUI and check Full Access permission the Service account is not there.
Add-MailboxPermission Service.account -User email@example.com -AccessRights FullAccess -InheritanceType All -Automapping $false
Any idea why it doesn't work?