[Dovecot] Dbox group file permissions

[Chris Lasater]

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."