Translated into English ''Hello everyone, please help me! I can no longer use Thunderbird. I don't understand what I can or should do; I'm a complete novice, and computers and I aren't exactly friends. I've been using Thunderbird for a few years, but now, for personal reasons, I had to delete and reinstall the application. I don't know what happened, but nothing works anymore. Every time I try, I get this error message: "Unable to connect to the server. The configuration, username, or password is probably incorrect." I eagerly await your help. Thank you all.'' Please use Google Translate to translate into English when using English forum. '''Check the following:''' '''Firewall: ''' If you reinstalled Thunderbird program then check your Firewall. This might be the default that came with the OS OR controlled by an Anti-Virus. * Access Firewall and set up Thunderbird program as an 'allowed' program. Otherwise it might be blocking access to required ports. '''VPN''' Check computer for a VPN. Many Anti-Virus now offer a VPN and in some cases it has been found to be auto enabled. Many servers do not like VPN as it hides your IP address and server thinks you might be a hacker - so you get blocked. '''check localhost''' If you are trying to connect to a server that uses Authentication Method = Oauth2, then make sure computer does not have anything using the localhost. Usually people who manage websites tend to have programs like Apache Xampp that use localhost - switch it off until OAuth has been set up. Servers that use Oauth are generally gmail, yahoo, office365/outlook I do not know what server you are talking about so advise is limited until you tell us. If using Oauth then you would also need to make sure cookies are enabled in Thunderbird. * Settings > Privacy & Security * Web Content * Select 'Accept cookies from sites' If you are trying to recreate an account previously deleted, then check the previously stored passwords have been properly removed. * Settings > Privacy & Security * Scroll to passwords section * click on 'Saved Passwords' * If you see any lines where the username = email address of account you are trying to add, then remove them and finally click on 'Close'. '''Now switch off the Account Hub:''' * Settings > General * Account Hub - * uncheck / do not select 'Create accounts in the new Account Hub' Now Exit Thunderbird - wait a few moments for background processes to complete. Start Thunderbird * Menu app icon > New Account > Email * Enter name., email address and password (usually same password as used to access your webmail account - but some servers now insist on app generated password) * click on 'Continue' Thunderbird by default will attempt to locate IMAP server settings. If you do not want IMAP, you need to make sure to select the Pop option and check the server settings are correct. If creating Oauth token then you will get a prompt to logon with password - just to prove you really are you and then a request to allow Thunderbird access to account. You will need to allow it.