[Dovecot] Auto-subscribe to folders

Hi

I will use autocreate plugin in a new installation, and client has asked me if the users can be auto-subscribed to certain folders. Example: the users will have an autocreated Junk folder (for SPAM) and we want the users not to be un-subscribed for this folder; so if the user wants to be unsubscribed (from outlook, webmail, etc), there are two options: a) the action is rejected or denied; b) the next time he/she logins, then the folder is autosubscribed again. Could this be done? How?

Thanks in advance.