Рейтинг 5 из 5 звёзд

OK, this time there's a real replacement.

https://addons.mozilla.org/en-US/thunderbird/addon/deselect-on-delete/

Рейтинг 5 из 5 звёзд

I used this extension for years and refused to update T-bird when a replacement was not available. I finally found a replacement. The extension Mail Tweak has a preference for "Deletion Behavior". The setting "nothing" does the same thing that Unselect Message did. It has a bunch of other cool tweaks too. The Mail Tweak extension is at Mozdev ... http://mailtweak.mozdev.org/.