Hi ktchong,
Delivery confirmation is not required by U-Pic in order to file a claim. A USPS receipt or proof of shipping will suffice.
The requirements for filing a claim are a signed affadavit from the buyer stating the item was lost or damaged, a completed claim form, and proof of carrier payment(like a receipt).
Complete claim forms and filing instructions can be found at http://www.U-Pic.com -> Claims.
-Mike