The issue of returning the Candidate's contact, telephone call or email after initial resume submission has always been one I have had strong feelings about. A Recruiter's ability to return to contact the Candidate after the initial resume submission has been significantly enhanced by Applicant Tracking Systems. The ATS does that for us.
What the Recruiter does after that is most critical in developing a viable network for the skill sets and experience the Recruiter is seeking. I am well aware that it is virtually impossible to contact everyone that has applied for the positions we are staffing. But it does not take much effort to have an email system facilitate contact with the Candidates that may not be "the ones", but yet valuable to the pipeline.
I strongly support setting aside part of the day to return those phone calls that come in and spend a brief amount of time with the Candidates that call. This will give you an opportunity to ask for referrals and gather other Candidate and market intelligence. It also does not hurt your efforts to be straightforward with the candidate and educate them as to why they are not a fit.
It has been my experience that a Candidate respects this and I will have begun to develop a valuable future resource of information from this person.