About two weeks October 13, 2015 this is the final day of mainstream support for Outlook 2010.
This is especially relevant to Exchange Online users as the system requirements for Office 365 state that it is designed to work with “any version of Microsoft Office in mainstream support”. While Microsoft does not actively block you from connecting to Office 365 with legacy versions or client applications, the text around older versions includes phrases like “does not recommend”, “limited support” and “quality of user experience will diminish over time”.
