Change required fields in php contact form

// Validate form fields
if(empty($email) || filter_var($email, FILTER_VALIDATE_EMAIL) === false){
$valErr .= 'Please enter a valid email.<br/>';
}

if(empty($valErr)){

<!-- Status message -->
<?php if(!empty($statusMsg)){ ?>
<div class="status-msg <?php echo $status; ?>"><?php echo $statusMsg; ?></div>
<?php } ?>

<!-- Form fields -->
<div...