Media Queries in GMX and email clients

Does anybody have any experience coding for these two German clients? Have just started working for a company in Germany which test for GMX and, and both clients seem to be completely ignoring the media queries.
As opposed to the GMail app, which just displays the desktop version of the email, these throw up a weird hybrid of desktop and mobile versions.

In this screenshot: you can see, albeit very small, how GMX compares to the desktop version on the right.

Thanks for any tips!

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