October 13 is new iPhone day. It's also the last day of support for Office 2010 and Office 2016 for Mac. After today's Patch Tuesday fixes and updates, Microsoft won't provide any further security updates, bug fixes or technical support for these products. Office 2010 and 2016 for Mac still can be used after today, but will no longer be officially supported.
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. 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.
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. But it changed its policy due to customer feedback in September 2018, allowing users to continue to use the Office 365 services with Office 2016 through October 2023.
A couple other Office support dates worth noting:
Microsoft recently announced it will be delivering new non-subscription (perpetual) version of its Office desktop clients for Windows and Mac in the latter half of 2021. These new perpetual Office clients will likely be branded Office 2022 if Microsoft sticks with past naming conventions. Microsoft also announced there will be another version of its on-premises Office servers coming in the second half of next year, but they will require a mandatory subscription for security updates, fixes and patches.