server.sh setting wrong PATH
server.sh sets:
PATH=/sbin:/usr/sbin:/bin:/usr/bin:/usr/local/sbin:/usr/local/bin:/usr/X11R6/bin
On my centos rpm based setup that path of maildirmake is
/usr/lib/courier-imap/bin/maildirmake
This means server.sh can't find it (btw no error about that in the log)
I fixed it by replacing the PATH line with
. /etc/profile
which will give the correct path's including path's added by rpm installs which place new paths in /etc/profile.d