Knockout Validation multiple email address

multiemail.js

ko.validation.rules['multiemail'] = {
    validator: function (val, validate) {
        if (!validate) { return true; }

        var isValid = true;
        if (!ko.validation.utils.isEmptyVal(val)) {
            // use the required: true property if you don't want to accept empty values
            var values = val.split(';');
            $(values).each(function (index) {
                isValid = ko.validation.rules['email'].validator($.trim(this), validate);
                return isValid; // short circuit each loop if invalid
            });
        }
        return isValid;
    },
    message: 'Please enter valid email addresses (separate multiple email addresses using a semicolon).'
};