GMX is just about the worst email provider I've ever had. Accounts blocked without cause, no customer service - the list goes on. Avoid GMX at all costs!
Tip for consumers: GMX.com is a TERRIBLE free email provider! Email accounts are routinely blocked without cause and there is absolutely NO customer service. My email account was blocked less than a minute after it was opened for absolutely no reason. It was later mysteriously opened again but almost immediately blocked again - also for no reason. All attempts to contact GMX were ignored in both cases. AVOID GMX EMAIL SERVICE AT ALL COSTS!