Still having the message-grouping issue: https://support.mozilla.org/en-US/questions/1385113 The dirty workaround worked for some weeks but now again Thunderbird has this really annoying behavior. This makes Thunderbird even more annoying than Outlook. Any progress on this? Will the setting be permanently saved in the future? And will it be easy accessible in the menu? Any chance this can be disabled by default? Looks like only 3 people in the whole world use this...and 8 billion people have to deal with this trouble. I run Thunderbird on 7 machines - both on linux and Windows...and this behavior really made it unusable. I really got into trouble since I didn't find messages through this behavior. Even I've overseen messages through this behavior. And when searching older messages, you can't sort them by date properly, since it's no straight timeline anymore... I really can't understand why this ever happened to Thunderbird, which was one (probably THE) best mailclients for more than 15 years now. But so it''s nearly completly useless and wastes time (and energy) every time for millions of users :(