Well, with the amount of email I get I suspect either my school sells my email address or companies get people to just download the entire directory. There's at least 4 companies that I get regular email from and I've never interacted with them before. Maybe they plan on mass emailing students about this new service.

While it sounds like I'm being critical of this service, I would have liked to see this before I graduated. I know a few people who joined startups but it's because they knew someone who knew about the startup to even apply. My school has an entire building for technology startups but there's no listing of who's hiring, or at least if there is one it's not very well known.