@MartinS: No, this is not yet fixed in 2.5.8, because it doesn’t make sense just to revert the changes introduced in 2.5.7. After all, this is a problem with Strato hosting and we have to find another more future-proof solution.
If you are on Strato hosting and want to update to 2.5.8, you have to apply the same changes as explained above.
Yep that´s what I meant, sorry, my question fell too short. So the same fix works for 2.5.7 and 2.5.8 and has to be applied in both since the proper fix is going to be introduced to 2.5.9
Thanks for clarifying!