According to Paypal via Google, Paypal do not send letters to postal addresses. They do though share postal address information with the person to whom you are sending money.
Scammers are getting cleverer all the time, matching information about us from different sources to catch us out. I find the TV Licence scam e-mails can look quite convincing to the unwary. The game is to contact a large number of people, whether the e-mail is relevant or not, in the hope that they will catch out a handful. Sadly, they do, often us 'maturer' adults.
I recently heard of a new scam where a courier delivers free flowers as a an incentive for you to subscribe as a regular customer. The only charge is a £3 delivery charge, payable by credit card so that the retailer knows that the courier has made the delivery. The credit card machine is a fake which simply records all your credit card information. This is used, before you know it, to fund a buying spree. . Simple, as the meerkat might say.