When a new Zuora tenant is created a couple of users are always created. Can Zuora stop making unnecessary/unusable/risky ar@... user accounts for "accounts receivables" on all the sandboxes and production tenants?
On all implementations of zuora I always see this account and I have never seen a customer who really has this email address.
It is not possible to deactivate it, because you can not activate. Changing the emailaddress is also not possible, because the emailaddress typically does not exist.
More in general:
In Zuora every user gets his/her personal login: this is great for tracking and tracing who did what action. Having a generic "accounts receivables" user is not advisable due to security/logging issues.