Just wanted to follow up on this for anyone who stumbles upon it.
In /etc/dovecot/conf.d/ you will find easyengine creates a 99-ee.conf file. I did not notice this at first and saw no mention of it in docs. Most but not all of mail stack install config changes for Dovecot are in this file. You also have to ssl = yes(or 'required') and uncomment dovecot.pem snakeoil in 10-ssl.conf. Also be mindful that the nginx webmail block is not ssl enabled( atleast it wans't for me) So careful trying out roundcube as you are throwing your password out there unencrypted.