I have used Firefox (Windows 10 ) to connect to GMX Mail with no problems for some years. Firefox is the browser I prefer to use all the time.
Recently, on both a desktop and a laptop, Firefox appears to be forcing me to the GMX smartphone App instead of the regular Windows-friendly site. This prevents me logging on to GMX Mail - it simply does not work on Windows.
I see this problem surfaced some six years ago, and must have been fixed, however, it now seems to have returned. It was agreed back then that it was a Firefox problem, not a GMX problem.
I can log into GMX with Microsoft Edge, and will have to use that for now, until the issue is fixed.
I ask that Firefox resolves this issue as soon as possible.