Security
Dovecot has been designed with security in mind. It uses multiple processes and privilege separation to isolate different parts from each others in case a security hole is found from one part.
Additional things you can configure:
Allocate each user their own UID and GID (see System Users)
Use a separate
dovecot-auth
user for authentication process (see System Users)You can chroot authentication and mail processes (see chrooting)
There are some security related SSL settings (see SSL configuration)
Set
first/last_valid_uid/gid
settings to contain only the range actually used by mail processes