https://techcommunity.microsoft.com/t5/exchange-team-blog/basic-authentication-and-exchange-online-june-2021-update/ba-p/2454827Update: On June 17, 2021, the Exchange Team announced that they are going to turn of basic authentication for tenants not using it. Update: On February 5th, 2021, the Exchange Team announced that turning off legacy authentication in H2, 2021 is postponed until further notice. When they resume the program, they will let customers know…