GMX emails are automatically deleted?

Hello!

Somehow, my emails keep getting automatically moved from my inbox to the deleted folder. I haven't set any settings, nor have I set a deletion interval or anything else. The emails are automatically deleted as soon as I'm in my inbox on my phone.

The strange thing is that I have several emails and the others don't have a problem, just one.

Does anyone know what I can do or has anyone experienced something like this before?