Manual Pages  — MAILER.CONF

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.

# Execute the "real" sendmail program located in
# /usr/libexec/sendmail/sendmail
sendmail        /usr/libexec/sendmail/sendmail
mailq           /usr/libexec/sendmail/sendmail
newaliases      /usr/libexec/sendmail/sendmail

Using Postfix (from ports) to replace sendmail(8):

# Emulate sendmail using postfix
sendmail        /usr/local/sbin/sendmail
mailq           /usr/local/sbin/sendmail
newaliases      /usr/local/sbin/sendmail

Using Exim (from ports) to replace sendmail(8):

# Emulate sendmail using exim
sendmail        /usr/local/sbin/exim
mailq           /usr/local/sbin/exim -bp
newaliases      /usr/bin/true
rmail           /usr/local/sbin/exim -i -oee

Using mini_sendmail (from ports) to replace sendmail(8):

# Send outgoing mail to a smart relay using mini_sendmail
sendmail        /usr/local/bin/mini_sendmail -srelayhost

Using dma(8) to replace sendmail(8):

# Execute dma instead of sendmail
sendmail        /usr/libexec/dma
mailq           /usr/libexec/dma
newaliases      /usr/libexec/dma
rmail           /usr/libexec/dma

postfix(1) ( ports/mail/postfix), dma(8) ( ports/mail/dma), exim(8) ( ports/mail/exim), mini_sendmail(8) ( ports/mail/mini_sendmail)