function checkf(contact) {

if (contact.name.value == "") {
alert("Please enter your name.");
contact.name.focus();
return false;
}
if (contact.email.value == "") {
alert("Please enter a valid return email address.");
contact.email.focus();
return false;
}
if (contact.subject.value == "") {
alert("Please select the subject of your enquiry.");
contact.subject.focus();
return false;
}

}