function validate_email(field,alerttxt) {
  with (field) {
    apos=value.indexOf("@");
    dotpos=value.lastIndexOf(".");
    if (apos<1||dotpos-apos<2) {
      alert(alerttxt);
      return false;
    } else { 
      return true; 
    }
  }
}

function validate_form(thisform) {
  with (thisform) {
    if (validate_email(email,"Not a valid e-mail address!")==false) {
      email.focus();return false;
    }
  }
}