[Dovecot] Info on Config Sharing or Unfied Config?

Is there a wiki page or other resource on configuration sharing between Postfix and Dovecot? Or is there a unified config file somewhere that I can use for mail components (like Postfix, Dovecot, Clam, and Spam Assassin)?

I'm finding that I need to add the same information in multiple places. For example, Postfix users go in /etc/postif/vmailboxes, but Dovecot uses a user/password database stored in /var/mail/%d/%u (or other methods). And the same certificates and keys get entered multiple times.

I think (or hope) there's something better, but I have not come across the resource.