Finding people actually interested in changing jobs is challenging. I'd say it's probably one of the hardest parts of recruiting.

All the engineers at https://www.MightySpring.com (we're building an app that matches companies with job seekers) spent this week doing traditional agency recruiting to get a better sense of the problem. Recruiting really is a numbers game. Finding the right balance between personalization and efficiency - knowing that most emails get deleted immediately, unread, is hard. We don't envy the recruiters who do this all the time.