The message about your password is, unfortunately, a rather specific-sounding message that in reality means a generic problem with your login. It can mean your user name is wrong, or that something (usually anti-virus or firewall) is preventing communication between Thunderbird and the server, or indeed that the password is wrong.

As you say you have confirmed your login credentials elsewhere, the anti-virus/firewall area would be where I would now look.

But I am not and never have been a Mac user so I'll have to leave it to someone else to offer you any relevant and specific guidance.

there is no firewall on this computer. also, since i put up this posting i re-installed thunderbird with my yahoo account and it is working with no problem. i am wondering if i put the wrong password in when i first logged in with the mac account and by doing so it turned off the account. i read somewhere you have to wait a couple of days and try again.

the login and passwords are fine. it's just something that thunderbird is blocking for whatever reason. if you have any ideas please let me know. and thank you for responding, Zenos.

Allow apps that use less secure sign in. https://help.yahoo.com/kb/SLN27791.html

Cross link by a forum moderator. I will also mark this solved and move the other post (the link will still work). drotar said /forums/lost-threads/712206

dealt with this for a week and finally figured out why i was getting error messages on my password being incorrect. With Sierra you are able to have a double password log in. if you opt for that feature your password on thunderbird will no longer work. that is because it is looking now for another one. to fix it simply go into mac sierra and opt for the single password protection. this entry has just saved you a week of rooting around trying to find a solution. that's what it took me.