Sounds like a fantastic racket for Kickstarter!
EDIT: I've read more of the comments and it sounds like IndieGoGo has nothing to do with Paypal. They were separate funding efforts, from the same landing page. "You can pay by IndieGoGo or Paypal."
I presume the reason I couldn't figure this out from the Mailpile website is that they stopped mentioning the PayPal option when it was clear that Mailpile wasn't going to get paid by PayPal in any kind of short order. You can pay IndieGoGo or you can send Bitcoins.
That's how I'd run my business if I didn't have a product yet. You'd have to be crazy to use PayPal for that.
EDIT2: I guess IndieGoGo does offer the PayPal option. I don't understand enough about how this is put together to have an informed opinion. If PPUSD and credit cards are all handled by PayPal, then it would seem that PayPal does indeed have some risk. Maybe it's actually accepting credit cards that's crazy. _THOSE_ have some serious anti-fraud guarantees, and there's more to fraud than simple non-delivery.