To do this, use one of the following procedures, as appropriate for your situation. You can check the connection status to verify this. This problem occurs when Outlook is connecting to your mailbox via MAPI over HTTP. It only occurs on Outlook, I agree with the moderator in the Office 365 Community forum that it should be an Outlook client issue.Īlthough it's for Outlook 2013, I think it should also work for Outlook 2016.