After installing latest Thunderbird, I attempted to set up to shadow the existing ATT account which is currently monitored via IMAP on both the web site and my iPhone (in hopes of replacing the web site). The automatic setup option ONLY showed the old POP account which I used years ago on the same email address ([edited] @att.net), so I went to manual configuration, where the default was POP but a dropdown list allowed me to select IMAP. The first attempt was no good, so I checked the settings for Mail on my iPhone (the ATT web site did not display any configuration at all). The hostname was shown as imap.mail.att.net, port 993, security was SSL (I selected SSL/TLS), the auth method was password, and my username was my email address. on the outgoing server, the iPhone had smtp.mail.att.net, port 465, which I copied, SSL/TLS, password, and my email address as username. the Re-test button also found those same settings (green message box). But the Done button, after a short delay, replied "Unable to log in at server. Probably wrong configuration, username or password." in a yellow message box. I cannot get any further than this, and have no idea where to turn. Both the iPhone and the web site on Windows 10 still work, with the same password (which I copied for the mail signin, so I assume that is the password which was submitted to the servers, since there was no place to enter any other passwords. James Allan Richardson [edited email and phone# from community support forum]