If you use the GMX Mail app and/or GMX
MailCheck or access your mail via POP3/IMAP, you need to log in again once. In addition,
the use of POP3/IMAP requires (re)activating access in the email settings. For more
information, please see Activate or deactivate POP3 and IMAP.
Info:
You will need the latest version of the GMX Mail app for
two-factor authentication. For more information, please visit GMX Mail App Versions.