Flag on SU to indicate who wants invoices to be emailed

Would be good if there was a boolean flag on the SU record indicating that the invoice should be emailed.. Then on the invoices screen it would simply be a case of selecting all invoices and using the bulk action to send the emails.. Those with the flag set will be processed and marked and those without the flag set will be skipped.. Will make the process a lot quicker than working through a separate list of who wants the invoice emailed to them.