IMAP inaccessible on Exchange Server 2013
If you are experiencing an issue where the IMAP clients are not able to connect on the Exchange Server 2013/2016 server, and when trying to telnet the 143/993 port the connection drops automatically, then this Tutorial may shed some light on your issue. The error message when trying to test IMAP connectivity is listed below.
Microsoft.Exchange.Monitoring.ProtocolException: Authentication failed. The connection is being closed.
Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.Server response while making connection:
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