jQuery.fn.rf_validate_email = function(){
    var state = true;
    this.each( function(){
        var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
        var address = jQuery(this).val();
         
        if(reg.test(address) == false) 
        {
            state = false;
            return false;
        }
    });
    return state;
}