IMAP Server Trouble using dovecot

Trouble using dovecot as IMAP server with OX-HE

There might be some trouble using OX-HE in combination with some versions of the dovecot IMAP-Server (we actually use version 10.0.10). The OX-Server uses two different IMAP commands to get the folder tree of an IMAP account, depending on where to show the tree. While using the 'LIST' command to get and show up the tree in the users' preferences page, it uses the 'LSUB' command when reading the tree for the users' webmail frontend. According to the RFC-3348 a IMAP server vendor MAY implement an CHILDREN extension, implementing the attributes "\HasChildren" and "\HasNoChildren" to ask the server, if there are subfolders in the currently listed one. Some servers - including the version 10.0.10 of dovecot (maybe some more) - do not implement this feature, so the OX webmail frontend will not show up the complete folder structure, but only the main INBOX content (emails). So because the IMAP connector of the OX server uses the LSUB command, which retrieves the folder structure by looking up for the "\HasChildren"-Attribute, the OX webclient does not show the folder structure, because dovecot answers with an empty list (see the following example with a telnet session):

kungfu:~ # telnet imap.bla-blupp.org imap
Trying 172.16.3.216...
Connected to 172.16.3.216.
Escape character is '^]'.
* OK Dovecot ready.
01 LOGIN fasteddy@bla-blupp.org 208899
01 OK Logged in.

01 LIST "INBOX" %
* LIST (\HasChildren) "." "INBOX"
01 OK List completed. 

01 LSUB "INBOX" %
* LSUB () "." "INBOX"
01 OK Lsub completed.

01 LOGOUT
* BYE Logging out
01 OK Logout completed.
Connection closed by foreign host.
kungfu:~ #

Best practice: - might be to use a lesser version of dovecot that implements the needed feature (still to test)

- is NOT to use the latest source to build customized imapd, because it does not work