[Dovecot] difference between namespace auto=subscribe and autocreate plugin

Hello.

I read docs, but still do not understand difference between following configuration options:

namespace inbox { # Create and subscribe to folder mailbox Drafts { auto=subscribe }

and `autocreate' plugin

plugin { autocreate = inbox.Drafts autosubscribe = inbox.Drafts

On wiki page that describes `autocreate' plugin i read: ... mailboxes that must always exist for all users.

So even if user delete Drafts IMAP folder on next connection server will create it.

Is `mailbox' undocumented feature? I see it only in configuration file, but wiki does not mention it.