Mine

base_dir = /var/run/dovecot/
protocols = imap imaps pop3 pop3s
listen = [::]
ssl_cert_file = /usr/share/ssl/certs/exim.pem
ssl_key_file = /usr/share/ssl/private/exim.pem
login_process_size = 16
login_processes_count = 3
login_log_format_elements = user=<%u> method=%m rip=%r lip=%l proto=%s pass=%w %c
login_log_format = %$: %s
first_valid_uid = 25
last_valid_uid = 0
first_valid_gid = 1
last_valid_gid = 0
mail_extra_groups = exim
default_mail_env = maildir:/home/maildir/%d/%n/Maildir:INDEX=/tmp/dovecot/%d/%n
maildir_copy_with_hardlinks = yes
protocol imap {
}

protocol pop3 {

}
auth default {
  mechanisms = plain digest-md5 cram-md5 apop
  passdb passwd-file {
    args = /etc/exim/domains/%d
  }
  userdb static {
    args = uid=93 gid=93 home=/home/maildir/%d/%n mail=maildir:/home/maildir/%d/%n/Maildir:INDEX=/tmp/dovecot/%d/%n
  }
  user = root
}