dovecot-pgsql.conf

driver = pgsql
  connect = host=localhost dbname=mail user=mailreader password=SECRET
#  default_pass_scheme = SHA512
#  default_pass_scheme = BLF-CRYPT
  password_query = SELECT email as user, password, 'maildir:/home/mail/'||maildir as userdb_mail FROM users WHERE email = '%u';
  user_query = SELECT '/home/mail/'||maildir as mail_home FROM users WHERE email = '%u';