Can't access maildir with dovecot

[Julien Cubizolles]

I'm a total newbie regarding imap servers. I'm trying to set up a
Offlineimap/dovecot/Gnus system and Gnus complains that it cannot access
the maildir... Here is my setup, put together by copying stuff from
around the web without any prior knowledge of these tools...

* Offlineimap is setup to use the $HOME/Maildir-free/, using
  
  --8<---------------cut here---------------start------------->8---
  preauthtunnel = /usr/lib/dovecot/imap -o mail_location=maildir:$HOME/Maildir-free
  --8<---------------cut here---------------end--------------->8---

  in the local maildir part of ~/.offlineimaprc.

* The Maildir-free maildir has been correctly (I think) populated
  with a single "General" folder. 

  /home/wilk/Maildir-free:
  total used in directory 52 available 5502852
  drwxrwxr-x   6 wilk wilk  4096 oct.  23 11:10 .
  drwx------ 240 wilk wilk 20480 oct.  23 15:06 ..
  drwxrwxr-x   2 wilk wilk  4096 oct.  23 11:09 cur
  -rw-rw-r--   1 wilk wilk   348 oct.  23 11:10 dovecot.index.log
  -rw-rw-r--   1 wilk wilk    51 oct.  23 11:10 dovecot-uidlist
  -rw-rw-r--   1 wilk wilk     8 oct.  23 11:09 dovecot-uidvalidity
  -r--r--r--   1 wilk wilk     0 oct.  23 11:09 dovecot-uidvalidity.5629f967
  drwx------   6 wilk wilk  4096 oct.  23 11:16 General
  -rw-rw-r--   1 wilk wilk     0 oct.  23 11:09 maildirfolder
  drwxrwxr-x   2 wilk wilk  4096 oct.  23 11:09 new
  drwxrwxr-x   2 wilk wilk  4096 oct.  23 11:09 tmp


* dovecot is not setup to start as a server (no script in /etc/rc*.d/)
  and I didn't configure anything in any /etc/dovecot/ file (maybe I
  should have ?)

* Gnus is supposed to access the maildir as an IMAP server through
  dovecot: I have:

  (nnimap "FreeOffline"
	 	(nnimap-stream shell)
	 	(nnimap-shell-program "/usr/lib/dovecot/imap -o mail_location=maildir:$HOME/Maildir-free")

  in gnus-secondary-select-methods
  
* I try to access this maildir as follows

/usr/lib/dovecot/imap -o mail_location=maildir:/home/wilk/Maildir-free/

* PREAUTH [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE SORT SORT=DISPLAY THREAD=REFERENCES THREAD=REFS THREAD=ORDEREDSUBJECT MULTIAPPEND URL-PARTIAL CATENATE UNSELECT CHILDREN NAMESPACE UIDPLUS LIST-EXTENDED I18NLEVEL=1 CONDSTORE QRESYNC ESEARCH ESORT SEARCHRES WITHIN CONTEXT=SEARCH LIST-STATUS SPECIAL-USE BINARY MOVE] Logged in as wilk
* LIST "" *
* LIST (\HasNoChildren) "." INBOX
* OK List completed.

As you can see, the "General" folder doesn't appear, and there is a
mention of "INBOX" even though there is no folder under this name (but I
guess that's a default for any IMAP system). Accordingly, Gnus only
displays a INBOX folder when browsing the FreeOffline IMAP server, and
complains that it contains no message.

What's the correct way to setup dovecot? Thanks for your help.

Julien.