As part of Microsoft’s plan to move all online services to TLS 1.2, they are retiring 3DES beginning February 28, 2019. As a result, connections using the ciper 3DES will not work.
You can get an overview of your TLS 1.0/1.1 and 3DES usage in Office 365’s Secure Score at http://securescore.microsoft.com
Remember that TLS 1.0 and TLS 1.1 are not supported since October 31, 2018. Fore more details see:
Radu Narita 