I know this is beyond my kin when it comes to contacts, however, Microsoft is in full break mode with Legacy Exchange and Outlook Classic.

Folks need to be planning forward as a race against time is upon us and move to eM Client, Microsoft began blocking EWS by default in October 2026 for 365 (aka online) and will completely shut down EWS in Exchange Online by April 2027. I'm sure Microsoft is likely to make Exchange on-prem history at some point and is certainly not innovating on this platform.

At this time we have learned so much from FireBase, REST and other like API Frameworks -- maybe its time add-on a new way to sync eMail and bring eM Client along. Open the Framework so that a Thunderbird Plug-in would be available.

The future looks bright for Linux but we need a non-Microsoft License for eMail Sync.