Thunderbird stopped working on my old Mac Mini (2014). I bought another used Mac Mini (2018), running on Sequoia 15.3, and hoped to install Thunderbird on it, but so far I can't. When I try to set it up, it says my account is recognized, but when I click done, I get the message "Unable to log in at server. Probably wrong configuration, username or password." I suspect it's the configuration. I tried my old Mozilla password, when that didn't work, I created a new one, but that didn't work for Thunderbird either. My email comes from my ISP — AT&T — whose email service is powered by Yahoo. When Thunderbird stopped working on my old computer. I started using MyYahoo email (same email address), but I'd prefer going back to Thunderbird, which is much better for archiving and directing incoming email to folders I create. Please help.