Re (insert position description)
I regret to inform you that your application dated …. for the above position has been unsuccessful and is no longer under consideration.
You'll appreciate that when large numbers of applications are received, only so many can be chosen to proceed to the interview stage.
Optional additional material
If you'd like feedback from our interviewers about the reasons for this decision, please contact me / Mr. / Ms ……. on the above phone number to discuss your application.
Note: It's becoming far more common for unsuccessful job applicants to enquire about the reasons for their applications, and many will apply several times to an employer they're targeting for a career position. Feedback is a positive learning process, and retains the interest of very motivated applicants.