Email attachments
With Outlook 2016, you can save time by easily attaching documents that you most recently used to your emails from the Ribbon. When you attach files from OneDrive, OneDrive for Business or SharePoint, you can share them as View only, or give the recipients Edit permissions, which helps them collaborate easily on one copy that everyone works on.
Outlook 2016 Groups (Office 365 work or school account)
With Outlook 2016 you can use Groups instead of distribution lists to communicate and collaborate with your team members.
Search
Outlook 2016 email search is faster, more reliable and provides improved performance. You can seamlessly search email across your local computer, Exchange 16 server or Office 365 Mailbox.
Use Clutter to sort low priority messages
Clutter helps you move low priority messages out of your Inbox so that you can easily scan for important messages. Clutter analyzes your emails, and based on your past behavior, determines the messages that you’re most likely to ignore. It then automatically moves those messages to a folder called Clutter so that you can review them later.
New Chinese and Japanese Default Fonts
In Office 2016, existing Japanese and Simplified Chinese fonts have been updated with a Unified modern look and feel across the primary authoring apps: Excel, Word, PowerPoint, Outlook Mail and OneNote.
EAI (Email Address Internationalization)
EAI is a Outlook 2016 feature that enables you to send mail to, or receive mail from any email addresses regardless of the language of the email address. International addresses work just like English email addresses, so you reply, send, and compose emails the same way.
Tell Me
Tell Me brings features and help topics to your fingerprints, and saves you the time you would normally use to look for a specific function on the Ribbon. You can type what you’re looking for in the Tell Me what you want to do box at the top of the Ribbon, and see results as soon as you start typing. Every keystroke refines the results so that you can choose what you’re looking for as soon as you see it. It will also give you the option to read help topics on the feature you're looking for, if you need more information.