[Dovecot] chdir failed, but requires group permissions

Using Debian Etch package dovecot-common and dovecot-pop3d, based on 1.0.rc15-2

My home directories are set up with 770 permissions as follows:

/home/<group name>/<user name>

Using this method, users MUST be a member of the appropriate group to access their own home directory. If they are not, they can't chdir past /home.

This appears to kill dovecot with a "chdir failed with id xxxx: Permission Denied" error, immediately after authenticating a pop3 user.

I was able to make a user the owner of the <group name> directory, and dovecot succeeded

But when the <group name> directory is owned by <group name>:<group name> and the user is a member of the group - the process dies.

Any suggestions?