Be careful using qmail. It is viewed as hostile by its behavior given multiple recipients (split into multiple messages and parallelize the output). It is also viewed by some as spam support because of its accept then bounce method of handling incoming mail.

At home I have it configured to drop anything not recognized into a spam mailbox, only allow certain source addresses to send, I ignore the parallelize issue (I don't have any mail lists that it would effect), and I give myself a little reaction time by storing things in an outgoing serialmail queue for 5 minutes (giving my outbound queue time to respond to a virus infestation or the like).