Microsoft Office 365 will enforce TLS 1.2 from October 2018, and any hybrid Exchange organizations with mailboxes spread across on-premise and Office 365 will stop communicating id the on-premise Exchange servers are not using TLS1.2. Many popular services are now enforcing TLS 1.2 for all access and integration services to provide the maximum cryptographic protection. There are known vulnerabilities in TLS 1.0 and TLS 1.1 that the latest version addresses while also improving security generally. If you are already on TLS but are not running TLS 1.2, then you should also plan to upgrade as quickly as possible.
If you are still running SSL as your cryptographic protocol, you should plan to move to TLS as soon as possible. TLS is the successor to the Secure Sockets Layer (SSL) cryptographic protocol and provides stronger security. The latest specification is TLS 1.2 as defined by the Internet Engineering Task Force (IETF) who control the protocol.
Transport Layer Security ( TLS) is a cryptographic protocol that is used to secure communication over a network.
