
Expect macOS Mojave 10.14 support to end in late 2021 If you have an ITFS-supported computer still running macOS 10.13 High Sierra, please visit this website ( MyAccess login required) for current available options on upgrading your Mac to macOS Mojave 10.14 or macOS Catalina 10.15: As a result, we are now phasing out software support for all Mac computers running macOS 10.13 High Sierra and will end support on December 1, 2020. Modern Authentication, a newer method of identity management that offers more secure user authentication and authorization, have ended support for Apple Mail on macOS High Sierra 10.13 and older versions.

Furthermore, Microsoft has made the announcement of ending support for macOS High Sierra 10.13 on future updates to Microsoft Office 365 for macOS. In keeping with Apple's release cycle, Apple will stop releasing new security updates for macOS High Sierra 10.13 following its full release of macOS Big Sur. Apple released macOS Big Sur 11 on November 12, 2020.
