Just for the record, in case it helps anyone else - I found a
workaround to my problem.
The problem is that spamd 3.1.0 insists on trying to create per-user
config files in its user's home directory, even when I tell it not
to, and this causes errors if its user has no home directory. I
logged this as bug 4739.
The workaround is to add "--virtual-config-dir=/tmp" to the spamd
command line. This tells it to put any per-user files into /tmp. It
doesn't actually create any files there - which is correct, because I
disabled anything that would have made it create files - but the mere
fact that this directory exists is enough to avoid the "mkdir /dev/
null: File exists" errors I had been getting.
- B
