Feedback to Candidates on non-selection

Content

Does anyone have some creative ideas on how to provide feedback to candidates as to why they were not chosen for a position?  We're obviously looking to do this somewhat systematically.  ie. Select a paragraph to include in an autocorrespondence that would tell the candidate that they didn't answer X prescreen question correctly, etc.  Also--are we restricted (via OFCCP) to what we tell the candidates?  This becomes quite a challenge for us when we have hundreds of candidates apply on a requisition.

I'd love anyone's thoughts on this.