function isValidEmail(email, required) 
{
    if (required==undefined) 
	{   // if not specified, assume it's required
        required=true;
    }
    if (email==null) 
	{
        if (required) 
		{
            return false;
        }
        return true;
    }
    if (email.length==0) 
	{  
        if (required) 
		{
            return false;
        }
        return true;
    }
    if (! allValidChars(email)) 
	{  // check to make sure all characters are valid
        return false;
    }
    if (email.indexOf("@") < 1) 
	{ //  must contain @, and it must not be the first character
        return false;
    } 
	else if (email.lastIndexOf(".") <= email.indexOf("@")) 
	{  // last dot must be after the @
        return false;
    } 
	else if (email.indexOf("@") == email.length) 
	{  // @ must not be the last character
        return false;
    }
	
    return true;
}

function allValidChars(email) 
{
  var parsed = true;
  var validchars = "abcdefghijklmnopqrstuvwxyz0123456789@.-_";
  for (var i=0; i < email.length; i++) 
  {
    var letter = email.charAt(i).toLowerCase();
    if (validchars.indexOf(letter) != -1)
      continue;
    parsed = false;
    break;
  }
  return parsed;
}