For representing the logical email folder structure, a Maildir++ format exists that was first implemented by the Courier mail server, thus sometimes also being referred to as the Courier format.Unfortunately, some ambiguity exists in documentation and various implementations, regarding how the logical email folders are to be stored inside the main Maildir directory, ie. inside the main email directory containing the three subdirectories cur, new and tmp.Assuming there are three email folders, INBOX, Sent and Trash, I have understood the canonical spec to mean the following filesystem folder structure:mail \     - cur     - new     - tmp     - .INBOX \              - cur              - new              - tmp(and likewise for .Sent and .Trash)Furthermore, assuming we have a deeper folder structure, say, a top-level email folder Chronological/2012/09, it would be stored as follows:mail \     - cur     - new     - tmp     - .Chronological.2012.09 \                              - cur                              - new                              - tmpIs this correct? Some docs are a bit ambiguous about this, and I've seen implementations vary: some store the top-level folders without the leading dot, and some create a new filesystem subdirectory for each subfolder level (rather than using the dots to denote a new logical level).
what is the correct Courier / Maildir++ email (sub)folder format?
email;imap;maildir