From:  http://www.freebsd.org/doc/handbook/users.html

First. You'll want a MTA installed. I have postfix.

Second: goto: http://wiki.dovecot.org/QuickConfiguration

1. prompt# cd /usr/ports/mail/dovecot

2. make install && make clean

3. That installed a config file.  /usr/local/etc/dovecot.conf

4. edit it and enable.

Start it up and test it out

prompt# /usr/local/etc/rc.d/dovecot onestart
 

5. Add,