Update 1/20/2022: We have edited this post for clarity based on customer feedback.
Over the last few years, we have invested heavily in Microsoft Graph to enable developers to access the rich data ...
Updated Jan 20, 2022
Version 5.0
Blog Post
This is a major announcement and has the potential to impact every Microsoft customer from the point onward where no new EWS App Registrations are possible.
Right now, the Exchange Web Services API is the only way to get full-fidelity (preserving all properties) email information into and out of Office 365 (see MS-OXWSBTRF). Without this capability, 3rd Party applications addressing backup, eDiscovery, and migration (including Tenant-to-Tenant) will simply not be possible anymore! Also, even if the Graph API is extended to support the missing methods, will MSFT switch to the same "paid" model to use the Graph API as with Teams?
Imagine the implications of an acquisition or divestiture scenario, where one needs to consolidate tenants and/or on- or offboard legacy data. Cost and Time implications might get enormous, and a lot of restructuring projects will never reach an ROI if suddenly the project costs and timelines multiply.