/**
* Reference: Sandeep V. Tamhankar (stamhankar@hotmail.com),
* http://javascript.internet.com
*/
function isEmailAddress(cadena)
{
var s = cadena;
var filter=/^[A-Za-z][A-Za-z0-9_.]*@[A-Za-z0-9_]+\.[A-Za-z0-9_.]+[A-za-z]$/;
if (s.length == 0 ) 
	return true;
if (filter.test(s))
	return true;
else
	return false;
}