How do we fix this problem so that we can continue using Thunderbird, which has our email records for some 10 years?  We do not want to use a Microsoft mail client unless we really have to!  I imagine we aren't the only ones with this problem, but I couldn't easily find it by searching help.
 Many thanks!

Our company email host uses Office 365 exchange. As of yesterday (26 May 2022) all emails were blocked to Thunderbird on our networked office PCs using Windows 10. We cannot send or receive email on Thunderbird (fortunately it still comes through to our iPhones). Our host hold us that Microsoft has "recently started blocking POP3 connections on software such as Thunderbird". How do we fix this problem so that we can continue using Thunderbird, which has our email records for some 10 years? We do not want to use a Microsoft mail client unless we really have to! I imagine we aren't the only ones with this problem, but I couldn't easily find it by searching help. Many thanks!