Hello there Berman.

Do you like to turn off threads to communicate better with your clients?okay.

Thread fix Open Settings and select the General tab. Scroll down to the bottom and click Config Editor. Type mailnews.default_view_flags into the search bar. Double-click the preference and change its number value from \(1\) to \(0\). Click the checkmark or press Enter to save.

Tip https://support.mozilla.org/en-US/kb/message-threading-thunderbird

Sorry but it didn't work. I did restart Thunderbird and checked that there was now a 0 in that setting. But when I opened a message, five other messages opened with it. Thanks for trying.

Hello there

it is possible that this one single map fix can work on this issue too. You might need to try this fix after the global fix didn't work well.

For a single folder: Click on the folder (like your Inbox). Click View in the top menu bar (or the application menu button). Select Sort by and choose Threaded or Unthreaded.