“Beginning January 12, 2016, only the most recent version of Internet Explorer available for a supported operating system will receive technical support and security updates. We will work to update and clarify our Office 365 system requirements soon and communicate this to you via Message Center.”
This is actually quite a bold statement from Microsoft, because you take a look at the August 2014 browser market share (http://www.w3counter.com/globalstats.php), the usage of previous versions of Internet Explorer is still quite high but Internet Explorer 11 only having a slightly higher market share than Internet Explorer 8 and 9.
If you take a look at the Office 365 System Requirements (also updated mid August) you will also notice the following statement:
Office 365 is designed to work with the following software:
- The current or immediately previous version of Internet Explorer or Firefox, or the latest version of Chrome or Safari.
- Any version of Microsoft Office in mainstream support.