We are running Exchange 2010 Enterprise (standard CALs), and are looking at a cloud archiving solution. Anything older than 1 year will be archived to the cloud. In order to clean up the mailboxes/databases I understand we will need to set GPO's to remove items older than 1 year. In setting the GPO, I can turn on the autoarchive function to run every <x> days and permanently delete the old items. My question is this: Is turning on the AutoArchive function enough to remove the older emails? Or do I also need to set Retention Policies on the Exchange server, and if so, is it required to have Enterprise CALS?