Apple Mail Version 16.0 / Sonoma 14.2

[rmschne]

The issue discussed often previously in this forum. I searched the forum “sonoma mail” and found a lot of hits, e.g.

Sending mail to DevonThink not working with macOS Sonoma and DVTP 3.9.3

The simple answer is: you can’t. Apple deprecated Apple Mail plugins and broke things for all third-parties who develop (and also sell) these plugins. There is nothing we can do about this. Drag and drop, mail scripts, and mail rule scripts are the first alternatives you could explore. DEVONthink’s View > Import sidebar will still work, albeit more slowly without the plugin.