opensmtpd forwarding sent mail and extras-pgsql

Hi,

I am planning a mail server of opensmtpd and dovecot. I'd be glad to know if there is any way to save a copy of mail to dovecot's "Sent" mail box before relaying them out.

I am also not about find any docs on opensmtpd-extra-pgsql. Is there any guide to link postgresql up with smtpd for virtual users?

Thanks
qwerjkl