We are in the process of migrating users from iMAP server with Rackspace to Exchange. It is a Hybrid environment as some users will be staying with the iMAP service (legal reasons). How the issue is we have migrated most of our users over and configured their accounts in outlook but they keep complaining that their messages arrive on their phones much faster then in the 2016 Outlook for Mac.
It if was a few seconds we would not have a problem but sometimes it is 10 minutes before the email appears in Outlook even with multiple 'send receive' attempts. The mailboxes range in size from having a few hundred emails to some of the larger accounts having 20k - 30k emails in the one account. Rackspace at this point is being not help.
Office 2016 will improve everything for the Mac users and therefore many of them seemed to request for the free download since Microsoft announced its availability on their blog. Once I had the Office 2016 installation file available the process went rather smooth at first. Only the Outlook setup took long.