Yeah, validation layer was one of the many, many issues with the system. Maybe a dating site type system...have an index of jobs and applicants. Free to send messages back and forth, completely anonymouse. Messages are "request for application", "application", "denial of application", "denial of request for application", "application accepted" (not you're hired, but the application was received and we're reviewing it), "request for screening" and "accept/decline screening". You can't send a message if you have one pending a response. Make it 100% free, charging money to increase the number of pending responses you can have and still send a message.

Don't mind the rambling...this is literally typing as I think.