Popper is the program that allows client email programs to fetch their email from this server -- the old way; via POP3. I've not messed with IMAP, so don't even ask.
First time only
] cd /usr/ports/mail/popper ] make
] make install
pop3 stream tcp nowait root /usr/local/libexec/popper popper
ps -axand find 'inetd', then do a 'kill -HUP ###' that pid.