Issue: When you use Outlook 2013 as your mail client and have an IMAP mail server, you stop receiving new emails. Your account will set up properly, and passes the initial connection test, but you can’t receive new mail. All your old messages are accessible and everything seems to work fine, apart from the fact that you’re not getting any new mail in your Inbox.
Solution: Add “Inbox” as your “Root folder path”. You can find this by opening up your account settings and digging into Change Account > More Settings > Advanced. On mine, it was blank. I entered “Inbox” per some advice I found buried online. Saved changes, told Outlook to check my email and everything started flowing again.