Thanks for reaching out Cactuspie,
It sounds like you tried using iCloud Mail, but the server was busy. We can help.
The best solution for this type of issue is to try again later. A server error means the issue isn't with your account or device, but instead the issue is with the Apple server that iCloud Mail uses. After some time, give it another try and see if there is any change.
If you continue to get this message, you can connect with Apple directly using either Get Support or if you're in a region without direct support options, you can also Contact Apple for support and service.
Hope that helps.
Take care.