Start Thunderbird and open the setup wizard via File > New > Existing Email Account.
Enter your name, email address and email password now.
Hint: If you do not want your password to be saved, uncheck Save Password.
Confirm your entries with Continue.
Thunderbird now automatically searches for the email servers in the Mozilla ISP database and enters the 1&1 IONOS servers.
Hint:We recommend that you use IMAP, as the emails remain on the 1&1 IONOSserver and can be retrieved, for example, on the go with your notebook or smartphone.