Email Required Error for New Billing Addresses in Authorize.net Payment Processing

[MMWM]

When clients log in to pay invoices and add a new billing address during checkout a new contact is created for that billing address but the contact does not have an email address. Then when trying to submit payment the authorize.net gateway returns an error stating that an email address is required.

Contacts cannot be created via the admin panel without an email address so not sure how this should work. I guess contact emails should not be required and the payment gateway should be updated to not error out on that or it should receive the main accounts email address for payment processing purposes.

Please advise or log as a bug.