To start off the new year I thought I'd look at how you can go about using some of the new features that are being introduced in Exchange Online. One of the big new features is Clutter which we all saw at MEC is Austin and is now being rolled out to Office365 tenants. If you don't know what clutter is check out http://blogs.office.com/2014/11/11/de-clutter-inbox-office-365/ but basically it is Machine learning (AI or skynet for the paranoid) for your Mailbox. Machine learning is one of the fruits of increasing processing power and also the cloud in that software development/rollout cycles are now more closely aligned to what hardware can do. Keep in mind this is just the start of what the technology can do, there is just so far tweaking UI's can go so this to me is where the really exciting future of the tech is and I'm looking forward to see where this goes in the coming year.
Back to the subject at hand when you enable Clutter you end up with a new folder in your Mailbox that hangs of the MsgRoot called Clutter (or the localized equivalent). While there are a number of new objects for Clutter in the new Proxy definitions in EWS there is no Distinguishedfolderid for the Clutter folder like most other Mailbox system folders. So to get the Clutter folder in EWS you will need to either search for it by name of a better way is you can use the ClutterFolderEntryId extended property which is available on the Mailbox's Non_ipm_root folder. When you request this property you will get returned the HexEntryId of the Clutter folder which you then need to convert using the ConvertId operation to an EWSId. You then will be able to bind to the folder as per usual. To put this together in a particular sample here are two example of doing this in c# and powershell. The following will get the Clutter folder and showing the number of Unread Email in this folder.