Hi to all!
We mailed our I-130 application to chicago lockbox and found out lately that we need to MAIL THE PACKAGE W?RETURN RECEIPT REQUESTED/DELIVERY CONFRMATION..we didnt do that. what we did is to mail it in express mail at USPS. is that ok? how can we know that the USCIS receive our application? pls let me know. we'll appreciate all your knowledge and comments

No problem. You're fine. Delivery confirmation, return receipt is just so that you can know when the package arrives. We sent our AOD using USPS express mail. I think there is a tracking number (check your receipt) you can use to tell when its been delivered.

The delivery confirmation is a personal choice like reeses said. No need to use it.

If you sent it USPS express then you should be able to track the package on the USPS website.