The rmail(8) program is part of the UUCP suite of software. It handles mail that comes in via UUCP, modifies some address information, and hands the result to sendmail.

The rmail program is supplied with the sendmail source distribution because most implementations of that program are deficient in many ways. The source for rmail is from BSD 4.4 Unix and is probably not suitable for other environments. If you actually run UUCP, and if you need a more robust rmail, you are encouraged to port this program to your system.

Because using or installing this version of rmail is not recommended, the default action of Build is to print the following when invoked:

% cd rmail
% ./Build install
NOTE: This version of rmail is not suited for some operating
      systems.  You can force the install using
      'make force-install'.

If you want to change this default action, you can do so by defining this confFORCE_RMAIL macro:

define(`confFORCE_RMAIL', `TRUE')

With this definition in your m4 file, the default action of Build changes to:

% cd rmail
% ./Build install
install -c -o bin -g bin -m 555 rmail /usr/ucb

which does the install. The owner, group, and mode are set with confUBINOWN (confUBINOWN), confUBINGRP (confUBINGRP), and confUBINMODE (confUBINMODE), respectively.