The IMAP4 backend role listens on 127.0.0.1:143
If we telnet 127.0.0.1:143or "localhost" we hit the IMAP backend service.
If we telnet the server on any other IP address on TCP143 we hit the IMAP front end service.
This is what is confusing. By default the IMAP4 frontend proxy server component is disabled even if the service is started.
If you telnet the server on its local IP address as shown below.
You will simply get a blank Telnet screen which will automatically close the session seconds after.
This happens as the ImapProxy frontend is disabled by default on the Server Component State of the server.
To enable it, use the following command.
Set-ServerComponentState -Identity Servername -State Active -Requester HealthAPI -Component ImapProxy
Need IT Support with Microsoft Exchange in Perth? Click Here.