Every road has its end and this also counts for software lifecycles. One ending cycle has a severe impact on Office 2016 Mac-users connecting to Microsoft 365-services.
Tastes are different and so is the way we use software. While I know many people that still use to buy their software once and use them for years, this behavior rather becomes difficult in the age of services and subscriptions. While you may get along with software components once bought quite good the local way, there may be some impact on services you try to access the „remote way“. In this case, Microsofts Cloud-services are affected and an on-premises-version of its Office-suite on the Mac as well.
Microsoft released an updated document about a month ago telling which components will be passed through a sieve within the next end-of-life-cycle starting on October 13th, 2020. While Redmond is doing ongoing investments to its cloud services, older Office-clients will reach their EOL-state. While is it already known that Office 2010 will be generally outdated on this day, just a few know that there will be problems with connecting to Microsoft's cloud with other Office-versions.
Starting on October 13th, 2020, only specific versions of Office will be supported for connecting to Office 365 (and Microsoft 365) services. These include Microsoft 365 Apps for enterprise (previously named Office 365 ProPlus), Microsoft 365 Apps for business (previously named Office 365 Business), Office 2019 (for example Office Professional Plus 2019) and Office 2016, such as Office Standard 2016. Examples for the specific online services are the well-known Exchange Online, SharePoint Online and OneDrive for Business.
The way how the offline components connect to the online services is TLS-encryption (version 1.2 is needed now while TLS 1.0 and 1.1 are retired) and the basic authentication with Exchange Online. In a footnote, Microsoft also shows further information like, for example, that versions of Office 2019 and Office 2016 are supported until October 2023 and that the support for Office 2016 for Mac is dropped at all. You won’t be able to connect to Microsoft 365 services from October 13th, 2020 on while Office for Mac in version 2016 isn’t supported at all anymore starting with this day.
While this document seemed to be a general one on the first view, the impact on Mac-users may be truly severe: You will rather have to update your Office-version to a 2019-version (which already got feature-freeze in 2018) or choose the subscription-way by entering the recurring billing-system of Microsoft 365 to stay with the latest, updated version of the Office-suite without restrictions.
While, by all means, an end-of-life-cycle is a well-known process of putting deprecated software to its grave, it should be pointed out that the impact on every Mac-user with Office 2016 connecting to Exchange Online, for example, is simply existing as connections to the online services won’t be possible anymore from October 13th on. There is still time to change tack but this often depends on changing your strategy whether you go into a subscription model (to always stay up to date) or stay with the good, old, but seemingly dying way of a one-time-purchase of on-premises software!