[solved] "DEVONthink.mailbundle" is no longer available on macOS Big Sur

In Apple Mail 14.0 of macOS Big Sur, “DEVONthink.mail bundle” of DEVONthink 3 is

“DEVONthink.mailbundle” cannot be opened because the developer cannot be verified

Is displayed and can no longer be used

Welcome @yoidoreo

Please update your software to DEVONthink 3.6. A Big Sur compatible Apple Mail plugin is included in it. Thanks for your patience and understanding.

1 Like

Unfortunately, the Big Sur version of the plugin is no longer working, either.

Which version of DEVONthink and of Big Sur do you use?

Big Sur 11.0.1 and DevonThink 3.6

What’s the build number of Big Sur? Unfortunately there seem to be different versions of Big Sur 11.0.1.

The exact build is Big Sur 11.0.1 (20B29).

That’s bizarre - under exactly the same circumstances (DT 3.6, Big Sur 11.0.1 20B29) that plugin works for me.

Have you tried restarting the Mac and then trying again to activate the plugin, or removing and reinstalling the plugin, or shouting at it? :flushed:

I think I might be tempted to delete the plugin in /Users/yourusername/Library/Application Support/Mail/Plug-ins/Bundles/Users/yourusername/Library/Mail/Bundles after closing both Mail and DT, then restart my Mac, and reinstall the plugin from DT (assuming DT realises it has gone, which I guess it would). I haven’t tried this, though, and I can’t promise it won’t distort the delicate balance of the planet.


Thank you, that did the trick. Deleting, not shouting, though I can recommend a good shout every now and then. Even more bizarre was that I had to boot into Recovery Mode to delete it. In regular user mode, I was neither able to read the file permissions nor delete it. Even with a root command sudo rm -rf I was denied with “Operation not permitted”.

For future folks running into this issue:
My only possible explanation is that I had temporarily disabled SIP over the weekend for a day or so, trying to get something else to work (I was trying to get Steam Input to install in Big Sur, unsuccessfully). I didn’t go anywhere near the Mail plugin but perhaps it got mangled in the process anyway.