function validaEmail(emailad){
    var exclude=/[^@\-\.\w]|^[_@\.\-]|[\._\-]{2}|[@\.]{2}|(@)[^@]*\1/;
    var check=/@[\w\-]+\./;
    var checkend=/\.[a-zA-Z]{2,3}$/;
    if(((emailad.search(exclude) != -1)||(emailad.search(check)) == -1)||(emailad.search(checkend) == -1)){
        return false;
    }
    else {
        return true;
    }
}