function check_email(address) {
  if ((address == "")
    || (address.indexOf ('@') == -1)
    || (address.indexOf ('.') == -1))
      return false;
  return true;
}


function verifyuser() {

if (document.addusergroup.yourname.value == ""){
  alert("You must enter your name.")
  document.addusergroup.yourname.focus() 
  return false; } 

if (document.addusergroup.youremail.value == "")  {
   alert("Please fill in your email address.")
   document.addusergroup.youremail.focus() 
   return false; }
else {
if (!check_email(document.addusergroup.youremail.value)) {
    alert("Email address is incorrect. Please enter your email again.")
    document.addusergroup.youremail.focus()
    return false; } 
    }

if (document.addusergroup.groupname.value == ""){
  alert("You must enter a group name.")
  document.addusergroup.groupname.focus() 
  return false; } 
  

}