During the Outlook 2013 beta, any messages I replied to would switch to showing the word [Draft] in front of them which for me was a GREAT feature.
On the release code however, for my Exchange 2007 mailbox, that feature STOPPED working. Draft replies are still stored with the message, but the [DRAFT] prefix text is no longer displayed completely defeating the purpose of the feature, and worse, making it even more likely than before that I would write a detailed reply to an e-mail only to have it go unsent!
The same Outlook client connected to an Office 365 e-mail address DOES display the draft text.
It even works with Google Apps accounts! Just not their own product. I can only assume this was done on purpose to push companies like mine off of Exchange 2007 and onto 2010 or 2013.
Internet searches for this topic have turned up nothing, so I’m hoping someone else can confirm or deny this theory.
Darren Myher's Blog 
I have the exact same experience. Used to work with the RC versions of outlook 2013, stopped working with the commercial version. Works with gmail over Imap.
I really miss this feature, hope someone will be able to identify a fix.
Add me to the list of those not able to have it show “draft”…i’m on Exchange 2007 as well (SBS 2008) and thought that the inline reply was great, but didn’t like that i had no idea what e-mails i’d started replyign to. Then i saw a video on the new Outlook and saw the “draft” on the message and realized my copy is missing that feature. It also doesn’t allow me to flag messages like the video shows…
Unfortunately this is by design. See the following KB article. http://support.microsoft.com/kb/2810093
Thanks so much for the link Stephen. I suspected as much, but it’s nice to see them acknowledge it. Too bad that there’s no migration path to move from Exchange 2007 to Exchange 2013 (as of this writing the tools just don’t exist).
Especially for SBS users.
It feels like a ploy to get people to upgrade, as opposed to something that doesn’t work. Obviously it worked in beta. But now they have 1 more “feature” you only get on newer server software.
Well that sucks.