Procmail is a Mail Delivery Agent (MDA), sometimes called a Local Delivery Agent (LDA). It is not a Mail Transport Agent (MTA) such as sendmail, Postfix, Exim, or qmail. Procmail relies on another application (normally the MTA) to run it and to pass each email message. Procmail can run other programs (generally called email filters), make decisions, and take specific actions depending on the content of the email it is processing. Procmail may also be invoked from .forward files, which are part of the sendmail local delivery system.
First, check if Procmail is installed. The following command will locate Procmail if it is installed in the system path:
$ which procmail
If the response indicates that Procmail cannot be found, it will have to be obtained and installed.
which: no procmail in (/bin:/usr/bin:/usr/local/bin:/opt/bin)
If the response lists an absolute path, then Procmail is installed:
/usr/bin/procmail
