function checkEmail(email) {
	var a = false;
	var res = false;
	if(typeof(RegExp) == 'function') { //Testen ob RegEx unterstützt wird
		var b = new RegExp('abc');
		if(b.test('abc') == true) {
			a = true;
		}
	}
	
	if(a == true) {
		reg = new RegExp('^([a-zA-Z0-9\\-\\.\\_]+)(\\@)([a-zA-Z0-9\\-\\.]+)(\\.)([a-zA-Z]{2,4})$');
		res = (reg.test(email));
	} else {
		res = (email.search('@') >= 1 && email.lastIndexOf('.') > s.search('@') && email.lastIndexOf('.') >= s.length-5)
	}
	return(res);
}