[Dovecot] which architecture to use?

Dear List,

Based on the following installed environment:

• OpenBSD (latest version!)
• PostgreSQL
• dovecot with SSL

would like to have a mail server which accepts system as well as virtual users and being able to connect to their mailboxes either via an MUA (Thunderbird etc.) or a web interface (squirrel mail?).

When using the web interface, non registered users should be able to creat e-mail accounts which will be dovecot virtual users!

Which components should I use?

Thanks