function isEmpty(s) {
   return ((s == null) || (s.length == 0));
}

function isLetterOrDigit (c) {
   var charpos = c.search("[^A-Za-zÀ-ßà-ÿ0-9]"); 
    if (charpos>=0)
		return false;
	else
		return true;
}

function isEmail (email_address) {
	   
    if (email_address.length < 5) {
        return false
    }

    at_location = email_address.indexOf("@")
    dot_location = email_address.lastIndexOf(".")

    if (at_location == -1 || dot_location == -1 || at_location > dot_location ) {
        return false
    }

    if (at_location == 0) {
        return false
    }

    if (dot_location - at_location < 2 ) {
        return false
    }

    if (email_address.length - dot_location < 2) {
        return false
    }
    return true

}