Hi,
Having a major issue with users from our on-premise exchange sending to our office 365 environment. Some users are able to send to addresses from the on-premise environment to the office 365 environment whereas other recieve NDR with the following error.
#550 4.4.7 QUEUE.Expired; message expired in unreachable destination queue. Reason: The mailbox recipient does not have a mailbox database ## exchange 2010
Im racking my brain to find a fix to this issue. Any ideas?
Thanks
Shane
