Q. "Do we need to keep all resumes and contact each person who applies?"
Answer:
When you accept resumes or applications in relation to a job, the resumes should be maintained for one year for compliance with an assortment of laws. Unsolicited resumes can be discarded but, if you have a practice of accepting unsolicited resumes, best practice is to save them for a year as well.
The amount of communication with applicants is entirely up to you. We recommend explaining in job postings what communication or lack thereof applicants can expect. As a general rule, no contact is needed (or typically expected) for unsolicited resumes and no contact is required in response to submitted applications.
Applicants at the later stages of the process will expect some kind of notification (email or letter) as a courtesy and while responses are not required, leaving applicants who do not get the position with a positive feeling helps create a positive reputation for your organization, so we recommend doing so whenever possible.