When I try to run spamd with:

/usr/sbin/spamd --virtual-config-dir=/home/spamassassin/%l -l --create-prefs --max-children 8 --helper-home-dir -d --pidfile=/var/run/spamd.pid

I get an error telling me that I have to use -u with --virtual-config-dir.  That doesn't work for my use-case.  Let me describe.

Of course, we have a mail server, where spamd runs.  That mail server NFS mounts the users' directories from their local machines (users' $HOMEs are on their local machines for performance reasons).

Due to the unpredictability of the state (off, suspended, etc.) of users' machines, we don't want to keep their spamassassin state_dir on their individual machines so we created a separate directory structure on the server for them.  i.e. /home/spamassassin/$user.

We do want to continue to allow the users to "own" their spamassassin data though so in each users' $HOME we link ~/.spamassassin back to the directory structure on the server over NFS.  So for example, on my workstation I have:

$ ls -l ~/.spamassassin
lrwxrwxrwx 1 brian brian 35 2011-10-16 09:17 /home/brian/.spamassassin -> /net/linux/home/spamassassin/brian/

Where /net/linux/ is an automounter map to the mail server.