Rated 5 out of 5 stars

This works on TB68 as expected, accept that when I open an email and then click its 'Delete' icon, or press the 'delete' key, the email is sent to the trash without a confirmation. (When selecting an email from the list view, and clicking the 'Delete' icon or pressing the 'delete' key, I do get the CBD delete confirmation as expected.)

Edit 2019-10-20: Version 1.2 is giving the proper confirmation message. Thanks for the quick fix.

This review is for a previous version of the add-on (1.1). 

I have fixed the issue in the next version 1.2.
You can download in advance the version 1.2 of ConfirmBeforeDelete here https://github.com/caligraf/ConfirmBeforeDelete/releases/download/1.2/ConfirmBeforeDelete.xpi
I expect the new version 1.2 to be available soon on https://addons.thunderbird.net/