Thunderbird Threaded View
In addition to gmail, I use Thunderbird for my business email (smooshylab.com) for a couple of reasons. Partially because I’m a bit old school and want to keep my business email “safer” and off of a public mail system like gmail, but I’m also holding out for that one day someone else will want to send encrypted email with me.
So, I decided to do some searching of the internets to find out if I could have a threaded view in TB and found an easy way to add it.
Go to Preferences->Advanced->General (or in windows, Tools->Options->Advanced->General), and click on Config Editor. In the Config Editor, search for the preference mailnews.thread_pane_column_unthreads. Double-click on it, which should change the value to false. Restart Thunderbird and click on the little swirly thingy in the columns.
Here’s a screenshot of the little swirly thingy:

By the way, feel free to send me some encrypted email to stan at smooshylab dot com. Here’s my public key.