hi r.e.g.
   when things like this happen it can be sometimes someone or something
   doing it as a matter of course: e.g. automated code or a paid job. they
   don't always reply (but occasionally have) as it doesn't further their
   ends to do so or they don't hear the request.
   I infer you're planning to regain access to your account after the lock
   expires.
   i'm not familiar with gmx, but I know many respectable people use
   protonmail. [1]cock.li and [2]riseup.net also respectable and normal
   here. I kinda miss mailservers hosted on anonymity networks, or that
   forward mail associated with anonymity networks, or personally hosted
   ala freedombox.
   it can also be good to retranslate one's text or adopt different
   writing and posting styles when posting anonymously. there are some
   pretty powerful tools for that but i'm not really familiar with them.

References

   1. http://cock.li/
   2. http://riseup.net/