I asked because I had the missing “manage” button problem too and it was a MacOS thing rather than a DEVONthink thing…
See: Can't use Devonthink Services in Mac Mail.app on Catalina - #6 by jbhutt
From @BLUEFROG:
This is an Apple issue. You can try this…
- Quit Mail.
- Open Applications/Utilities/Terminal
- Paste: sudo defaults write “/Library/Preferences/com.apple.mail” EnableBundles 1
- You’ll need to enter your administrative password to do this.
- Type: exit and quit Terminal.
- Launch Mail and check the Preferences > General.