The file
/etc/mailer.conf contains a series of lines of the form
name program [
arguments ...]
The first word of each line is the
name of a program invoking
mailwrapper(8). (For example, on a typical system
/usr/sbin/sendmail would be a symbolic link to
mailwrapper(8), as would
newaliases(1) and
mailq(1). Thus,
name might be “sendmail” or “newaliases” etc.)
The second word of each line is the name of the
program to actually execute when the first name is invoked.
The further
arguments, if any, are passed to the
program, followed by the arguments
mailwrapper(8) was called with.
The file may also contain comment lines, denoted by a ‘#' mark in the first column of any line.
The default mailer is
postfix(1), which will also start by default (unless specifically disabled via an
rc.conf(5) setting) so that locally generated mail can be delivered, if the “sendmail” setting in
/etc/mailer.conf is set to “/usr/libexec/postfix/sendmail”.