Major responsibility that United Postal Service (UPS) takes on its shoulder is to insure your packages that has been lost/damaged from them by mistakenly.
The package lost/damaged may be containing important documents or we can say every package is important for person to person it depends on.
How would you know that package has been lost? The answer to this question is if you didn’t receive your package within 24 hours of excepted date of delivery than you can report to the UPS that your package has been lost as you didn’t received within 24 hours of mentioned date.
You can request them for the claim the time it will be approved then only you will paid for your package up to its cost.