Nobody here knows how much of Airbnb's growth is driven by Craigslist, it's purely speculative. Until Airbnb confirms, you'll never know but you'd have to be naive to believe that you can build a company up to $1 billion by firing off a bunch of emails. Nobody here has even suggested the possibility that "Airbnb became a billion dollar company" by suggesting how many Craigslist rentals are posted each day, along with a standardized conversion rate.

I'm surprised to see how negative the comments are on this. This is like Yelp paying people to write reviews. Shady? Sure. Illegal? The only part of the CAN-SPAM Act Airbnb broke was (1) not including a physical mailing address, (2) not mentioning it was an ad, and (3) not including an unsubscrive link. Otherwise, CAN-SPAM is laughable at best. It's hardly enforced. Don't expect Craigslist to come at Airbnb with a lawsuit, it'd probably not hold up in court.

I see this instead as one of Airbnb's many tactics to try and reach out to users. If you look at this logically, they've been covered by the press a lot. The amount of growth they might (or might not) have reached doing this would hail in comparison to how much they obtained by press and simple product and customer development.