Hi all, We have 2 servers (master web server + ispconfig and slave mail server) in multiserver setup. I added IPv6 addresses and everything works except synchronization between servers. When I add mailbox it still wait in the queue. I created new mysql user ispcsrv2 on the master server with IPv6 address of slave server which solved the error "mysqli_connect(): (28000/1045): Access denied" but synchronization still not work. When I turn on debuging there is no error in cron.log. When I remove IPv6 addresses from servers config the synchronization works again. What did I overlook? Any idea please?