Send email for pending post

I did a bit more research and this is what is working for me now.

The admin will only get an update if a pending post is added or updated.

add_action( 'transition_post_status', 'pending_post_status', 10, 3 );

function pending_post_status( $new_status, $old_status, $post ) {

  if ( $new_status === "pending" ) {

    $post_title = get_the_title( $post_id ); 
     $post_url = get_permalink( $post_id ); 
     $subject="A post has been updated"; 
     $message = "A post has been updated on your website:\n\n";
     $message .= "<a href="". $post_url. "">" .$post_title. "</a>\n\n"; 
     //send email to admin 

     wp_mail( '[email protected]' , $subject, $message ); 
  }

}