dovecot - Oct 2013 - Dbox group file permissions

Hi everyone,
     I feel like I am missing something obvious here.  I have dovecot up 
and running and every piece of mail is given user read/write 
permission.  I see the option mail_gid, but I do not see anyplace to set 
the group permissions.  I see the below wiki talking about new home 
directories getting their permission from the parent directory, but this 
does not seem to work.  Any assistance would be appreciated.

http://wiki2.dovecot.org/SharedMailboxes/Permissions

I changed the group permissions on the parent directory, and used rm -rf 
to delete the user directories, then logged in again so it was recreated.

[user at dovecot ~]$ sudo ls -la /mnt/home/imapd/domain.example.net/
total 24
drwxr-x---  6 imapd imapd  4096 Oct 21 17:35 .
drwxr-xr-x 46 imapd nagios 4096 Oct 21 16:55 ..
drwx------  3 imapd imapd  4096 Oct 21 16:59 user1
drwx------  3 imapd imapd  4096 Oct 21 17:35 user2

Setup
Mail is written in dbox format
CentOS 5.9
dovecot 2.2.6
NFS with director

Mail Configs
mail_home = /mnt/home/imapd/%d/%n
mail_location = dbox:/mnt/home/imapd/%d/%n
mail_uid = imapd
mail_gid = imapd
Thanks,
Chris

Just in case someone else has the same problem, I had to change the 
following two variables

mail_home = /mnt/home/imapd/%d/%n
mail_location = dbox:/mnt/home/imapd/%d/%n

to
mail_home = /mnt/home/imapd/%d/%n
mail_location = dbox:~/


"When mail_location begins with%h  or~/, its permissions are copied from
the first existing parent
directory if it has setgid-bit set. This isn't done when the path contains
any other %variables."