saslauthd will do what you want ... it still supports pluggable backends for passwords. sasldb is just a backend.

Okay. But isn't ``auxprop'' supposed to do that without having a separate daemon running (which I'd prefer to avoid as it's on an already overloaded Pentium 166)? And if so, why isn't it working?

I understand that the daemon probably deals with concurrent access better, but this is just for home use, and another daemon means more wasted memory and process time; there's very little concurrent access to the mail system.