I to have this and usually how I filter between junk and making a trip. I truly hope this stays free.USPS sends me an E-mail whenever something is delivered to my mailbox (usually with a photo of the piece of mail or package) but, if it's just a flyer or junk then sometimes no picture.
This means I don't need to check everyday..... only when there's something worth the trip.
The service is free.
My only worry is when FedEx or DHL has to handle my package.