"There are a ton of new features. First off, as we reported a few days ago, Microsoft’s Clutter tool that separates your non-essential email from your most important emails will now be enabled by default for all users. As a reminder, you can help train Clutter by manually dragging messages into the Clutter folder.
Outlook will also now be able to throw out search suggestions as you type, allowing you to refine your search based on sender, folder, date and attachments. It’ll also now highlight your search results to make it easier to find key terms. And if you flag emails to read later, you can check them all out through the new Task module in the app launcher
Composing email gets a lot better too. You can now copy and paste images directly into the body of your messages, and links will now show previews with embedded webpages and videos. If you want to work on more than one message at a time, you can pop out messages into new window."