Determines if user is subscribed to see this folder.

A Boolean value.  

object.Subscribed [= value]

The Subscribed Property syntax has these parts:

UNIX systems may have much more folders available in user's home path, so there was a way to select only folders that are interesting enough to be used for mail storage. Therefore, IMAP specification declares 'subscribed' flag to folders that will be available to the client, and that clients selected.

When you connect using your client to any IMAP server, you will notice that you have to select folders that will be monitored and accessed by the client. Some IMAP servers will store information about subscribed folders locally, and some will just request client to make list of subscribed folders again and again.

In wodImapServer, there's really no point of making more folders than user actually subscribes - since you have to add them manually in each connection, but anyway, for compatibility reasons, subscribed property tells you if user is interested in this folder or not.