Notification support for the email provider GMX

[update-freak]

📢 What is the name of the service?
GMX

🔗 Provide some details about the service that can help with it's development.

• Homepage: https://www.gmx.net
• API Reference: ?

💡 Anything else?
I think this site would be helpful for the implementation: https://hilfe.gmx.net/pop-imap/imap/imap-serverdaten.html