Insider level Version Current Build Release Date
(formerly Insider Fast)
1712 8828.2006 December 7, 2017

Version Release date Highlights
Version 1712 (8828.2006) December 07, 2017 New features and improvements

  • In Outlook, we've made improvements to groups. Conversations load faster than ever and you can double-click to open the latest message in its own window.
  • By popular request, in Excel, you now have the option to deselect cells that you accidentally clicked without having to start over.

Source: Update history for Office Insider for Windows desktop - Office Support