I have a question: I have an Ipad, an iPhone and a normal laptop - on the two Apple devices I use the Apple Mail program (I have my GMX account up there) and on the laptop I go to gmx via the Internet. But now it is the case that when I get an email, I would like it that if I delete it on one device, that it is also deleted on the other (in the programs). That's not the case.
Make sure that email retrieval is synchronized via IMAP:
https://hilfe.gmx.net/pop-imap/imap/index.html
Thanks that is a good idea, because I see that my pop is set to me, but if I go to the link and follow everything, the pop account will always be set up automatically and if I want to switch to imap it is no longer possible
This could be related to your GMX tariff. But there's also a free one with IMAP support.
Thanks I did it already: https://mizine.de/ipod/gmx-imap-ipad-iphone/
Congratulations!