I have migrated from exchange 2010 to exchange 2016. In Exchange Admin Center there is an old System Mailbox(xxxx) which points to the old Server (found under normal mailbox display). When i try to delete this mailbox i get an error from AD INSUFF_ACCESS_RIGHTS. how can i delete the old mailbox. New ones are generated i have checked on the new exchange server.
This was an old Systemmailbox and i have deleted this MBX now with ADSI-Edit under following tree
"root" -> "CN=Microsoft Exchange System Objects" -> "CN=Exchange Install Domain Servers" and "CN=Monitoring Mailboxes". It Looks like CN=Microsoft Exchange System Objects CN=Exchange Install Domain Servers CN=Monitoring Mailboxes CN=SystemMailbox{6......} delete this entry
Now this mbx is not displayed anymore and no error in displaying user mailboxes.