There is a small bug in qmail-local.c which can lead to problems under very specific, rare circumstances with a .qmail file. See URL above for details. It's a simple one-line fix; I'm attaching an (untested!) patch which should take care of it.
Created attachment 14383 [details, diff] Patch to qmail-local.c I've tested that this patch applies and compiles, but not that it actually /works/ in a live qmail install. Please double-check my work. ;)
coming in -r11 shortly.