We use the linux mail server with courier-imap and client „bad“ Outlook 2013.
If you have problem with incoming emails to Outlook 2013, is here some things for recovery:
- unsubscribe IMAP folders and again subscribe
- delete subscribed file on mail server (in my case is, courierimapsubscribed) -sometimes do not need this (trouble is in the client side)
- add INBOX as root path for imap folders, FILE – Account Settings – Account Settings – Change – More Settings – Advanced (this works with courier-imap on server)