Dovecot configuration is split into multiple files under /etc/dovecot/conf.d/ directory with one main /etc/dovecot/dovecot.conf file.
Access to Dovecot is configured through PAM in /etc/pam.d/dovecot which authenticates and gives access to system user accounts.
Check non-default settings:
Dump all settings to stdout (useful for filtering with grep):
Default configuration listens on all IMAP/IMAPS and POP3/POP3S ports (143/993 and 110/995).
By default Dovecot logs to syslog using mail facility  which normally outputs to /var/log/maillog file.
Dovecot default configuration is fully functional for local user. However, according to the mail storage location setting by mail_location, it may be required to create /home/user/mail directory with appropriate permissions as Dovecot tries to access it:
mkdir /home/user/mail chown user:mail /home/user/mail chmod g+rwxs /home/user/mail