function checkEmail(field)
{
	var i = 1;
	var fieldValue = field.value;
	var fieldValueLength = field.value.length;

	if ( checkSpace(field, "Email address should not have space.") == false )
		return false;

	// look for @
	while ((i < fieldValueLength) && (fieldValue.charAt(i) != "@"))
		i++;
	
	if ((i >= fieldValueLength) || (fieldValue.charAt(i) != "@"))
	{
		alert("Please enter a valid email address."+fieldValue.charAt(i));
		field.focus();
		return false;
	}    
	else
		i += 2;
  
	// look for .
	while ((i < fieldValueLength) && (fieldValue.charAt(i) != ".")) 
		i++;
  
	// there must be at least one character after the .
	if ((i >= fieldValueLength - 1) || (fieldValue.charAt(i) != ".")) 
	{
		alert("Please put in a valid email address.");
		field.focus();
		return false;
	}
    return true;
}