Hello I'm dovecot bigginer from courier-imap.

I used shared maildir in courier like this.

1. create maildir

maildirmake -S /home/shared

2. create maildirshared file

echo 'SHARE /home/shared ' > /etc/courier/maildirshared

(use tabcode)

3. edit imapd config file IMAP_UMASK=022 IMAP_SHAREDINDEXFILE=/etc/courier/shared/index

in courier, only 3 step work .

I read http://wiki.dovecot.org