I recently realised that my yahoo has not been receiving email since April. (seldom login to this Mac). Yesterday when I login, I notice that emails were not coming in to my yahoo account. Firstly, I removed the yahoo account and tried to set up the account again but it kept prompting : 'unable to login at serve. Probably wrong configuration, username or password.' (picture attached) So I uninstalled and reinstalled Thunderbird from scratch again. (latest version now) That became worst as all my gmail account was suddenly faced with the same problem of not being able to be set up in Thunderbird. A pop up window says 'Secure Connection Failed' when I click on the 'done' button. Even tried to click on the 'or you can add an exception' and when nothing happened, I close the window and clicked on the >configure manually button. And it went back to the same yellow portion of the image :'unable to login at server. Probably wrong configuration, username or password.' (pls see attached pix) I then proceeded to add it manually anyway and the 'email inbox folder' appeared but there was no mail. Now all my gmail and yahoo accounts cannot be set up in Thunderbird at all. I have already added Thunderbird app in my yahoo as well as gmail so it is suppose to recognise that I am using Thunderbird as a 3rd party app. By the way, I have 2 Macs and I am using Thunderbird with all my accounts in on the other one (Mojave) just fine. I am not too sure what happened to this. This current Mac's OS is BigSur. Please help!