Weel , I guess I could have settled with
since I dicovered that somehow, during all my tries to reinstall, I was suddenly obliged to enter firstname.lastname@example.org instead of just username as before when logging in.
Either way, I took the long way round and migrated the accounts off of zimbra by exporting calendar ics's and setting upp a temporary imap server which I could drag and drop to in thunderbird. Then
and did a fresh install. Kinda tedious since I had to redo all the tweaking and configuration.
mv /opt/zimbra /opt/zimbra_bak
On the other hand, it usually gets better the second time around