function checkEmail (theField, emptyOK)
{  if (!isEmail(theField.value)) return false;
   else return true;}

// Returns true if string s is empty or whitespace characters only.

function isWhitespace (s)
{   var i;
    var whitespace = " \t\n\r";
    if (s=="") return true;
    for (i = 0; i < s.length; i++)
    {   var c = s.charAt(i);
        if (whitespace.indexOf(c) != -1) return true; }
    return false;}

// Email address must be of form a@b.c
function isEmail (s)
{   
   	i=0; while((s.substring(i,1)==' ')&&(i < s.length)) i++;
	s=s.substring(i);
	i=s.length; while((s.substr(i-1,1)==' ')&&(i > 0)) i--;
	s=s.substring(0,i);


    if (s=="") return false; 
    if (isWhitespace(s)) return false;
    
    var i = 1;
    var sLength = s.length;


    while ((i < sLength) && (s.charAt(i) != "@")) { i++ }
    if ((i >= sLength) || (s.charAt(i) != "@")) return false;
    else i += 2;
    while ((i < sLength) && (s.charAt(i) != ".")){ i++}
    if ((i >= sLength - 1) || (s.charAt(i) != ".")) return false;
    else return true;
}