1. Go to My account and log in.
2. Under "Mijn instellingen" ▸ "Profiel" ▸ "E-mailadres", click on "Bewerken".
3. Enter your new email address and confirm by clicking on "Wijzigingen opslaan".
After doing so, you will receive an email confirmation to your new email address. Simply follow the link in this email to confirm the change.