Two-factor authentication with MailCheck for Firefox
You need the latest version of MailCheck in order to use
two-factor authentication. You must first uninstall older versions.
Info:
The procedure described here is required only if you wish to use two-factor authentication
with MailCheck for Firefox and you have already installed
and use MailCheck.
Click on the Menu button and then on
Add-ons.
Select the Extensions category.
Select GMX
MailCheck, click on the three dots and then click on
Remove.
Restart Firefox.
You have removed the old version of MailCheck. In
the next step, you must install the latest version.