Employers may get a lot of applications for a single opening, but that doesn't exempt you from responding to prospective employees when they send in their resume. Seventy-seven percent of applicants will think badly of a company that doesn't respond to their job application, according to SmartRecruiters. It is in the company's best interest to take the time to respond. You may be able to manage your correspondence a little better by having your applicants submit applications electronically.
Set up an email address that is used only for job applications. Use your company's email provider, or use a free email service such as Gmail or Yahoo. To make it easier to remember, consider including "Job" or "Recruiter" in the email title, such as "CompanyXRecruiter@email.com."
Include the email address in your job posting and instruct applicants to send their application materials to that address. Also include a note in the job posting that lets applicants know you won't be able to respond to all inquiries, but that qualified candidates will hear from you by a specified date. By including instructions and a date, you might cut down on the number of applicants who contact you to inquire about their applications.
Set up an auto-response when applicants send an email to the specified email address. For email providers such as Gmail, you can do this by navigating to your "Settings" pane and setting up a "Vacation Responder." In the automated message, inform applicants that you've received the email and that you will contact qualified candidates by the specified date -- similar to the information you provided in the original job posting.
Call the applicants with whom you want to conduct an interview and set up a time to meet with them personally.
Copy and paste the email addresses of the candidates you don't want to hire into the "BCC" field of a new email message, so that the recipients don't see each others email addresses. Put your own email address into the "To" field. In the body of the email, state that you have narrowed down your list of candidates, and they are not being considered for the job. Most applicants never hear back from prospective employers, so this is a step up from the treatment they will get elsewhere.
If you're using a paper application process instead of electronic means, send a postcard or letter to each applicant to let them know you received the application and that you've moved on to other applicants.