Link to the article by Microsoft:
Microsoft announced that 365 apps and services will no longer support Internet Explorer 11 (IE 11) by the summer of 2021.
- Beginning November 30, 2020, the Microsoft Teams web app will no longer support IE 11.
- Beginning August 17, 2021, the remaining Microsoft 365 apps and services will no longer support IE 11.
This means customers will have a degraded experience or will be unable to connect to their Microsoft 365 apps and services on IE 11. For degraded experiences, new Microsoft 365 features will not be available or certain features may cease to work when accessing the app or service via IE 11. This change will be difficult for some users but they believe customers will get the most out of Microsoft 365 when using the new Microsoft Edge. Microsoft is committed to helping make this transition as smooth as possible.
Customers have been using IE 11 since 2013 when the online environment was much less sophisticated than the landscape today. Since then, open web standards and newer browsers—like Microsoft Edge—have enabled better, more innovative online experiences. Microsoft believes that 365 subscribers, in both consumer and commercial contexts, will be well served with this change through faster and more responsive web access to greater sets of features in everyday toolsets like Outlook, Teams, SharePoint, and much more.