As a Wave Super User, you will be contacted in the event that a Wave-generated email is not reaching its intended recipient and bouncing back. Depending on the reason, you can take a few easy corrective actions.
If Wave notifications are bouncing for a user that has been onboarded, check to see if the user's email address is current. If for some reason the email address has changed since you onboarded the user, confirm with the user their new email, then update the user's profile in the User Management Console and resend the onboarding email. Please be sure to alert the user that an onboarding email will be sent to them.
If the user has left the company, then you can deactivate the user.