function isEmail(str) {
	// are regular expressions supported?
	var supported = 0;
	
	if (window.RegExp) {
		var tempStr = "a";
		var tempReg = new RegExp(tempStr);
		if (tempReg.test(tempStr)) supported = 1;
	}
	
	if (!supported) 
		return (str.indexOf(".") > 2) && (str.indexOf("@") > 0);
		
	var r1 = new RegExp("(@.*@)|(\\.\\.)|(@\\.)|(^\\.)");
	var r2 = new RegExp("^.+\\@(\\[?)[a-zA-Z0-9\\-\\.]+\\.([a-zA-Z]{2,3}|[0-9]{1,3})(\\]?)$");
	
	return (!r1.test(str) && r2.test(str));
}