WooCommerce: Add Content to a Specific Order Email

/**
 * @snippet       Add Text to Customer Processing Order Email
 * @how-to        Get CustomizeWoo.com FREE
 * @author        milangru
 */
  
add_action( 'woocommerce_email_before_order_table', 'bbloomer_add_content_specific_email', 20, 4 );
  
function bbloomer_add_content_specific_email( $order, $sent_to_admin, $plain_text, $email ) {
   if ( $email->id == 'customer_processing_order' ) {
      echo '<h2 class="email-upsell-title">Get 20% off</h2><p class="email-upsell-p">Thank you for making this purchase! Come back and use the code "<strong>Back4More</strong>" to receive a 20% discount on your next purchase! Click here to continue shopping.</p>';
   }
}

if ( $email->id == 'cancelled_order' ) {}
if ( $email->id == 'customer_completed_order' ) {}
if ( $email->id == 'customer_invoice' ) {}
if ( $email->id == 'customer_new_account' ) {}
if ( $email->id == 'customer_note' ) {}
if ( $email->id == 'customer_on_hold_order' ) {}
if ( $email->id == 'customer_refunded_order' ) {}
if ( $email->id == 'customer_reset_password' ) {}
if ( $email->id == 'failed_order' ) {}
if ( $email->id == 'new_order' ) {}