@Ricardo I did work on something similar, maybe a year back - that time NetSuite said it is an enhancement to update the email template that NetSuite use to send email for gift certificate orders. We had the option to send email from our web store so we wrote a script in NetSuite to uncheck the "send email" for orders having gift certificate items - this was to make sure that customers get the email in a format that can be controlled by us and that too only once. Obviously, this approach won't work if you enter orders directly in NetSuite or if you cannot edit email template even in your web store - in both cases, you will have to live with what NetSuite is sending as email.