2018年10月31日付で、Microsoft Office 365 は TLS 1.0 および 1.1 のサポートを終了します

[fefrei (Felix Freiberger)]

Just as a reference of what others are doing, GitHub (which admittedly has an audience that is rather likely to keep browsers up to date) is disabling TLS 1.0 and 1.1 now:

Weak cryptographic standards removal notice