/* ================================================================= */
Edit /etc/rc.conf and set

proxsmtpd_enable="YES"

to enable proxsmtpd. 

Also, there is a proxsmtpd.conf-sample in %%PREFIX%%/etc/, 
rename to proxsmtpd.conf, otherwise specify -f option to your
config file. 

To work with postfix, See also
http://memberwebs.com/nielsen/software/proxsmtp/postfix.html
/* ================================================================= */