The connection between the Client Access server and Mailbox server "%1" failed. If this event is logged infrequently or only ...

The connection between the Client Access server and Mailbox server "%1" failed. If this event is logged infrequently or only during scheduled downtime for a Mailbox server, no user action is required. If this event occurs repeatedly, check network connectivity using PING or PingPath. Also, check connectivity using the Test-ActiveSyncConnectivity cmdlet. More information: 

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