I'm using version 140.0.1esr on macOS Sequoia 15.3.2. The problem is very simple. When I compose an email, hitting return puts me at the center of the next blank line. If I type, the text is all centered from this point on. Thunderbird didn't do this in the past, so I either inadvertently changed a setting, or the behavior of Thunderbird has recently changed. I really have no desire to spend time getting to know Thunderbird better. Like most people, I want to compose completely unstructured text-based email. (If I ever wished to add structures, which I doubt I ever will, I'd prefer markdown to HTML, like everyone else in the known universe ...) Ideally: there is an easy fix by changing a setting. Second best: There is an alternative email program to Thunderbird, perhaps text based, that can read Thunderbird mail archives. Third option: There is an early version of Thunderbird that still runs on current versions of Mac, before Thunderbird began including text formatting in email composition (along with all of the other distractions that have be degrading the quality of Thunderbird for a very, very long time).