Postfix

Postfix is a sendmail server. You can use it to send mail.

You may also be interested in dovecot (mail server - receive).

Tutorials

send-only SMTP server

https://sbcode.net/prometheus/smtp-server/

Locations

/usr/local/etc/postfix/main.cf	Primary Postfix Config
/usr/local/etc/dovecot.conf	Primary Dovecot Config
/usr/local/sbin	Executables Location

Examples

postfix example: sendmail only

References

Simple Dovecot/Postfix Server Instructions	https://www.vultr.com/docs/simple-mailserver-postfix-dovecot-sieve-freebsd-10
O'Reilly Definitive guide to postfix	(see textbook in calibre)
FreeBSD Postfix Setup	http://www.area536.com/projects/complete-freebsd-mail-server/postfix-youve-got-incoming/
All Commands	http://www.postfix.org/OVERVIEW.html