We've had several billers request that the email address(es) shown on the A/R/Collections tab be visible within the billing wizard (like you can see multiple address blocks) so they can see who the invoice is being emailed to, or that an email is not populated when they select the option to email a bill within the wizard.
This will help keep the data updated as well as reduce the amount of errors when doing bulk fee printing/emailing because there isn't an email populated in the client details.