This is my favorite add-on and I used it constantly in my workflow to manage my emails. Big thanks to opto for keeping it function despite major changes to the Thunderbird code and architecture that require significant re-writes by opto.
I consider Thunderbird broken without this functionality. I process 100's of emails daily and this add-on makes it super easy to scan an email and file it away for future reference.
Opto actively develops and maintains this add-on. Issues get fixed and improvements happen! Thank you for such a useful add-on.
Just made my second financial contribution in as many months.