jQuery validation plugin multiple email addresses

<form id="form" method="post">
Het e-mailadres van je vriend(in):<input type="text" name="emails" id="emails" class="emails"><br />
<input type="submit" value="Verstuur">
</form>
jQuery.validator.addMethod(
    "multiemails",
     function(value, element) {
         if (this.optional(element)) // return true on optional element
             return true;
         var emails = value.split(/[;,]+/); // split element by , and ;
         valid = true;
         for (var i in emails) {
             value = emails[i];
             valid = valid &&
                     jQuery.validator.methods.email.call(this, $.trim(value), element);
         }
         return valid;
     },

   jQuery.validator.messages.multiemails
);

$("#form").validate({
     rules: {
                emails: { required: true, multiemails: true }
            },
     messages: {
                    emails: {
                                required: "enter the email",
                                multiemails: "Not Valid email"
                            }
               }

});