Maybe after the update to kopano 8.7.0 i have no access to kopano.
In Server.log i found
Fri Feb 1 08:45:05 2019: [warning] LDAP (simple) bind on cn=server2,cn=dc,cn=computers,dc=meinedomain,dc=de failed: $Fri Feb 1 08:45:05 2019: [crit ] Cannot instantiate user plugin: Failure connecting any of the LDAP servers
Fri Feb 1 08:45:05 2019: [crit ] Unable to instantiate user plugin
without having it tested myself: the script that can be seen at https://stash.z-hub.io/projects/K4U/repos/kopano4ucs/browse/server_password_change.d/70kopano is responsible for updating the password. This is installed into /usr/lib/univention-server/server_password_change.d/. I would say that you should run this script manually (e.g. with ./70kopano postchange) to update the password in your system.