I use CONTROL=%h/Maildir/dovecot/public/control/[namespace] for each of my public namespaces. A few nights ago, I noticed having a new user subscribe to public folders for the first time will silently fail, becuase the path up to the subscriptions file will not be created. I am pretty sure dovecot used to create it for me, but maybe that changed in a recent version, or maybe I did something to break it? Work around is to mkdir -p /home/[user]/Maildir/dovecot/public/control/[namespace] but I'd like to avoid having to do that. Once I create the directory and make sure it is writable, the client can subscribe to public folders in that namespace. If they do not have permission, it still silently fails.

namespace: type: public separator: / prefix: #shared/decs/ location: maildir:/egr/mail/shared/decs:CONTROL=%h/Maildir/dovecot/public/control/decs:INDEX=%h/Maildir/dovecot/%q/public/indexes/decs list: yes subscriptions: yes