Sends an invoice receivable email with the given email information
Basic authentication header of the form Basic <api_key>, where <api_key> is your api key.
Email subject line
Reply-to email address
List of email addresses to send the invoice to
List of email addresses to send the invoice to
List of email addresses to CC on the invoice email
List of email addresses to CC on the invoice email
Optional custom message added to the invoice email body
default response