Email Id Validation in PHP?

<?php
$email = "[email protected]";
if(eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$", $email)) {
  echo "Valid email address.";
} else {
  echo "Invalid email address.";
}
?>