I'm one of the members affected, as I use an email address from GMX. I can confirm that I got a private message from Jellybean today, telling me what is also stated here.

Now I wonder what the technical problem could be, as the email protocol is a long established standard, and I never heard of "incompatibilities" that prevent email servers from exchanging their mail traffic.

Anyway, I accept the decision of the owner and moderators. But I will probably not be able to provide an alternative address that quickly, as my existing addresses are with GMX, and setting up a new address with a new provider is cumbersome. So for the time being, I will probably not be able to retrieve a new password, if I should forget the old one.