Microsoft announced in February 2018 that business users would need Office 365 Pro Plus or Office 2019 clients in mainstream support to access the Office 365 back-end services. Microsoft won't block customers using older Office client variants from connecting to Microsoft 365/Office 365 services, but it has warned those who do so won't get all the latest feature updates and fixes. In addition to reminding Mac users that support for these two perpetual Office versions ends today, Microsoft also is repeating its guidance that users are advised to go with Office 2016, Office 2019 or Microsoft 365 Apps (formerly known as Office 365 apps) to connect to back end Office 365 services. Office 20 for Mac still can be used after today, but will no longer be officially supported. After today's Patch Tuesday fixes and updates, Microsoft won't provide any further security updates, bug fixes or technical support for these products. It's also the last day of support for Office 2010 and Office 2016 for Mac. Windows 11 FAQ: Release date, requirements, price - plus when and how to upgrade.What is Microsoft 365 (formerly Office 365)? Everything you need to know.Can your PC upgrade to Windows 11? This Microsoft app could help you find out.