Just installed Exchange Server 2010 RC and when trying to test it with my outlook in POP3 configuration I received this error:
"Task 'firstname.lastname@example.org - Receiving' reported error (0x800CCC0F) : 'The connection to the server was interrupted. If this problem continues, contact your server administrator or Internet service provider (ISP).'"
The problem was that for some reason after installing Exchange Server 2010 RC, service Microsoft Exchange POP3 did not start automatically, so I had to open services.msc (via "run"), and start this service manually, also changed its startup type to Automatic for future. This solved the problem.