Fund hold release delivery confirmation?

[m4r1j4v45cr1p7]

I just sold a copy of Microsoft Windows XP on ebay for $75. Paypal is holding the funds, which I expected (as they almost always do). I was like "Okay, no big deal, I'll ship it and wait for the positive feedback or the delivery confirmation.". Well, I shipped the product today via USPS Priority Mail in a Flat Rate envelope. So then the buyer tells me they don't always leave positive feedback right away. So, if they don't leave positive feedback right away, how would they go about confirming delivery? Please help! Thanks.

[surplusdealdude]

Normally, you ship with delivery confirmation - that allows you to prove that the item was delivered ( it's available from the Post Office at a small additional charge)