As previously announced, beginning October 31, 2018, Microsoft will enforce use of TLS 1.2 with Office 365. TLS (Transport Layer Security) provides communications security over computer networks and so affects email, instant messaging, and other networked communication interactions. Windows 10, Server 2016, MacOS, and current versions of the major browsers have TLS 1.2 enabled by default. Please see the details below regarding older operating systems and browsers.

When Office 365 disables support for TLS 1.0 and 1.1, all apps and servers that interact with it must use TLS 1.2 or later versions to be able to connect without issues to Office 365 services.

Operating Systems Windows 10, Server 2016, and macOS have TLS 1.2 enabled by default. No changes are needed.

Most Windows 7 computers need to have a Recommended Update applied, as do Windows Server 2008 and 2012 (see below for information about updating Windows 7 and Windows Server).

Email  Current email applications such as Outlook 2016 and Apple Mail make use of their operating system’s TLS handling, and no changes are needed. Outlook 2013 for Windows issued an update in 2015 to add TLS 1.2 support. Updating to Outlook 2016 is recommended.

Web browsers  When accessing Office 365 through a web browser, the browser’s TLS is used. Current versions of the major browsers have TLS 1.2 enabled by default.

Some older browsers may support TLS 1.2 but may require that a setting be activated to enable its use. See the documentation from the browser's vendor to see how.

Updating Windows 7 and Windows Server 2008 and 2012 to support TLS 1.2

Other Windows 7 Computers and Windows Server 2008 and 2012 Microsoft recommends applying update (KB3140245) through Windows Update.

You can also download the update from the Microsoft Update Catalog.

More information about this change may be found in Microsoft’s announcement.