function validateEmail ( f )
{
  if ( isEmail ( f.email_address.value ) == false )
  {
    alert ( "Please enter a valid email address." );
    f.email_address.select ( );
    return false;
  }
  return true;
}

function isEmail ( string )
{
  if ( string.search(/^\w+((-\w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+$/) != -1 )
    return true;
  else
    return false;
}