Old Outlook versions: No more access to Office 365/Microsoft 365 services as of Nov. 1, 2021

[English]Quick note for users who are still running older versions of Microsoft Outlook. Microsoft has just reminded you that these versions will no longer have access to Office 365 and Microsoft 365 services as of November 1, 2021. Minimum requirements must be met to access the services.

It was announced on August 27, 2021 in the New minimum Outlook for Windows version requirements for Microsoft 365. Microsoft reminds users that it's not far off until November 1, when the minimum version requirements for connecting Outlook for Windows to Office 365/Microsoft 365 services will change.

• After November 1, 2021, only Outlook 2013 Service Pack 1 (with the latest fixes) and higher will be able to connect to Microsoft 365 services.
• Outlook 2007, 2010 und Office 2013-Versionen vor 15.0.4971.1000 werden dann nicht mehr unterstützt und können nicht mehr auf die Dienste zugreifen.

The reason for this exclusion is that Microsoft wants to make communication more secure. This will require some changes, which will cause problems with older Outlook features. Older versions of Outlook such as Outlook 2007 and 2010 are not compatible with the following upcoming service changes, and will therefore be blocked.

• Support for Basic Authentication will end (see also my post Disabling Exchange Online Basic Authentication in 2021). To increase the security of Microsoft 365, modern authentication protocols will be used.
• Microsoft is working to add support for HTTP/2 in Microsoft 365. HTTP/2 is a full-duplex protocol that reduces latency through header compression and request multiplexing. On the service side, Microsoft will be able to better prioritize requests and deliver data to clients more effectively. 

Based on usage data, Microsoft could see that the number of old Outlook versions in requests has dropped sharply. Microsoft is aware that some customers can't just not give up the old Outlook versions. Microsoft's customer support team is therefore actively reaching out to the tenants that use Outlook 2007 and 2010 the most. These users should be moved to newer, supported versions. In general, Microsoft is encouraging users to upgrade to the following versions:

• Office 2013: move to version 15.0.4971.1000 of Office 2013 (Service Pack 1 with the October 2017 update) 
• Office 2016: switch to version 16.0.4600.1000 of Office 2016 (with the November 2017 update, KB 4051890).

So for Office 2007 and 2010, you can only upgrade to the above Microsoft Office versions or to Office 2019 to continue using Office 365/Microsoft 365 services from Outlook. (via)