Cachetur will monitor the deliverability of emails sent to your account. If your email server starts to reject emails sent to you, cachetur will automatically invalidate your email address.
When this happens, you have to either correct the issue (tell your email provider to stop blocking emails to cachteur.no, add @cachetur.no to your allow-list) or change to a different email address.
To receive less emails from cachetur.no, disable notifications in your user settings.