custom scripts+Google docs email automatic response

Services required: Google Mail, Google Form, Google Spreadsheet Create custom script on Google spreadsheet that links to a form and automate an email response back to the email address merge-tagged with a unique value. userflow: 1. Administrator copy and pastes 8 digit voucher codes in Column E from another source (e.g. all the way to row 1000) 2. Anonymous fills out a form with First Name, Last name, Email address and click submit. 3. Email addresses gets inputted onto the spreadsheet by the system; script validates the email address and sends an html response along with a value in column E (one voucher code) to that email address. *if email address is not valid, don't send the email. *one email submitted gets one unique voucher code only, no voucher code should be sent to two different addresses. *only one submission is allowed from the same email address