I have following problem on a server running Open-XChange5 on SLES9, with Cyrus as imap service:

A userX tried to move a folderY (with more then 3000 mails in it) in outlook from a subfolder to the top of his inbox. This operation got completely wrong, with as result that the folderY(with all its mails) is not visible anymore in outlook, webmail, thunderbird, ... althought I still find the folderY as a directory in /var/spool/imap/userX, with all the files representing the mails. Also with lm in cyradm, the folderY appears in the list. How can I get it back visible for my mail clients ?
Should I run reconstruct on the userX mailbox. I never used the command before. How critical is it ?

All folders in IMAP must be a subfolder of "top" folder. You can move your "invisible" folder back and see it again. Folder you need typically named "INBOX".

Also you can try setup client to see all folders, but it is bad idea, because client can see "service folders" (e.g. trash, spool folder)

My "invisible" folder is a subfolder of /var/spool/imap/user/userX, so it should appear as folder in the Inbox, but that is now exactly the problem : in the email client, the folder is not visible.

maybe you need to subscribe that new folder.

Yes, meanwhile I solved it and indeed that was the problem : the subscription to that imap folder was gone. After subscribing, I got everything back.

Thanks