function checkform(){

    if (document.mailing.name.value=='') {
        rc=alert('Your name is required.');
        return false;
    }
    if (document.mailing.address.value=='') {
        rc=alert('Your address is required.');
        return false;
    }
    if (document.mailing.postcode.value=='') {
        rc=alert('Your post code is required.');
        return false;
    }
	    if (document.enquiry.email.value.indexOf('@')==-1) {
        rc=alert('Your e-mail address is required.');
        return false;
    }
     if (document.mailing.vehicle.value=='') {
        rc=alert('What type of vehicle are your interested in?');
        return false;
    }
     if (document.mailing.marketing2.value=='') {
        rc=alert('Your feedback is important to us. Please tell us how you found out about YVF.');
        return false;
    }
  
    return true;
}