Mail werkt niet meer

Go to your email providers website and login, what ever it might be. This is where you orginally set up your email.

Since you can log into the Apple Communities you should also be able to use iCloud email as a alternative until you get your other email figured out.

Delete the account in Mail and re-enter it.

I doing from North America, you might have better chance at resolving your question on of of the Apple Communities closer to you.

Apple Support Communities in Other Langua… - Apple Community