Already done... and same result.
I've restored my backup and it (almost) works... mails are sent and received but I can't create or delete users account through the adminUI (server error).
Doesn't matter, I'm going to install a new server and upgrade zimbra to NE edition next week and then use imapsync method to import mailboxes.
But I think, if you can post solution for this thread problem, maybe it will help somebody else in the future
Thanks for your answer anyway.
Loïc |