[Exim] Users with no home directory.

I've got some users who have no home directory, but have one listed in the
passwd file as having one as some stuff (including exim I think) objects
to having a null entry in the directory field of the passwd file.

This not existing is kicking out the userforward and localuser
directors with messages like:

failed to stat /home/bob (No such file or directory)
and
No such file or directory: failed to chdir to /home/bob

I've tried using ignore_enotdir within the userforward director but to no
avail. (doesn't seem to make any difference)

Is there any way to make exim not care if users' home directories don't
exist?

As a tempoarary bodge I've set all the users in quesion a empty dir as
their homedir. Is there a better solution?

Ta,
Alex.