Thanks gents. Why, oh why, do the logs report "vchkpw: some message" if it isn't running vchkpw... what is a noob to do when his system lies to him? I can't very well reprimand it.
Based on your advice of the compile order, I recompiled each package, in this order: qmail vpopmail couriour-authlib courier-imap Whether by compiling them in the correct order, accidentally fixing permissions, or by grace of God, it works. Incidentally, how would I discover what user the authdaemond is running as?