Edit the file:

/usr/local/etc/courier-imap/imapd.cnf
/usr/local/etc/courier-imap/pop3d.cnf

and fill out the necessary fields.

To create the SSL-imap certificate be sure that the file /usr/local/share/courier-imap/imapd.pem not exists, then run:

cd /usr/local/share/courier-imap
mkimapdcert

To create the SSL-pop3 certificate:

cd /usr/local/share/courier-imap
mkpop3dcert