Hi @Thomas_Kaiser and welcome to the Forum 
The verification email should be sent to your new email address, can you confirm this is the mailbox you’ve checked?
More info on adding your email here: How to Control Your Profile Settings in Asana | Product guide • Asana Product Guide
If you’re still running into trouble, please contact our support team, they will be able to manually add this email address for you; unfortunately due to security reasons, we’re not able to resolve these issues directly in the Forum!