FIXED 1. Close Thunderbird: Make sure the application is completely closed. 2. Locate your Profile Folder: C:\Users\[Your_Username]\AppData\Roaming\Thunderbird\Profiles\ 3. Find the profiles.ini file: Inside your Thunderbird profiles directory, locate the profiles.ini file. This file lists all your Thunderbird profiles. 4. Find the correct profile folder: The profiles.ini file will show you the name of your profile folder, which is typically a string of random letters and numbers followed by .default-release (e.g., abcdefgh.default-release). Go into that folder. 5. Delete the residual information in the file: Inside your profile folder, look for a file named prefs.js ('''BACKUP FIRST''') and open it with a text editor. Search for your email address or the domain of your email provider. You are looking for a line that starts with something like user_pref("mail.server.serverX.hostname", ...); where X is a number. This line holds the incoming server information that is causing the conflict. '''Carefully delete the entire block of lines related to your email account'''. It will be a set of lines with mail.server.serverX and mail.account.accountX that match your email. If you're not comfortable editing the file, you can try deleting the entire file, but this will reset other preferences as well. My X = 3 user_pref("mail.server.server3.check_new_mail", true); user_pref("mail.server.server3.clientid", … user_pref("mail.server.server3.directory", … user_pref("mail.server.server3.directory-rel… user_pref("mail.server.server3.hostname", … ... Best regards, Jose