var inputEmail:String = "[email protected]";
trace("inputEmail: "+inputEmail);
trace("isValidEmailAddress: "+isValidEmailAddress(inputEmail));

function isValidEmailAddress($str:String):Boolean {
	return (($str == findValidEmailAddress($str)) ? true : false);
}

function findValidEmailAddress($str:String):String {
	var pattern:RegExp = /\b[\w\.-]+@[\w\.-]+\.\w{2,4}\b/gi;
	var result:Object = pattern.exec($str);
	return ((result == null) ? "" : result[0]);
}

AS3 Checks a String to see if it is a Valid Email Format

regex, email, format, regexp

ActionScript 3