In an official blog post, Microsoft details the revamped IMAP feature in Outlook 2013, which is a part of the Office 2013 productivity suite. Microsoft listened to feedback gathered by angry Outlook users who were frustrated with the "lack of quality" when it came to IMAP and Outlook.
"Syncing/sending messages is done in the background, so you no longer have to wait for sync to complete in order to use Outlook. General comments about Outlook's performance when using IMAP was the top issue we heard from all of you, and we believe this change will improve the experience quite a bit," Microsoft stated in an official blog post. New mail notifications are now supported with IMAP in Outlook. Outlook 2013 will now allow you to choose how much mail to sync and how much to keep locally. On the downside of this new revamped support for IMAP, Outlook 2013 will no longer support Download Headers Only mode for IMAP or Categories for IMAP accounts.
"We were able to make these improvements to IMAP because you continue to provide feedback to the Outlook team about how to make your experience better. All your questions and comments are not only appreciated, but used to make decisions about how we can improve Outlook in the future. Please keep it coming!" Microsoft said. So good work to those who made this happen!