Does right clicking and selecting save as work? Does restarting with add-ons disabled from the help menu enable the drag and drop?

It's still the same - drag&drop is not working even when I restarted with Add-ons Disabled... Right-click and select Save As... works, but drag&drop is a time-saver

I still require help on this.. The Drag&Drop functionality of the email messages from ThunderBird client on mac to Mac Desktop is NOT working. Thanks!

Restart Thunderbird with add-ons disabled (Thunderbird Safe Mode). On the Help menu, click on "Restart with Add-ons Disabled". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender.

I have not installed any 3rd party Add-ons, only Lightning by default which I have disabled it, but to no avail. Still the same problem :(

Did you restart. I am not interested in your perceptions of what is installed. safe mode is about more than add-ons.

You might also not be aware that what support is provided here is provided by volunteers, no one here gets paid. so short answers that provider no useful information are often ignored, as are those demanding.

I did restarted the app in safe mode, but it still the same.

Apparently it works with attachments but not with messages:

https://bugzilla.mozilla.org/show_bug.cgi?id=1455429