The procmail package contains procmail, formail, lockfile and mailstat. procmail is an autonomous mail processor. It performs all the functions of a MDA (Mail Delivery Agent). formail is a filter that can be used to format mail into mailbox format. lockfile is a utilitiy that can lock a file for single use interactively or in a script. mailstat prints a summary report of mail that has been filtered by procmail since the last time mailstat was ran.