The connection to server was interrupted.
postfix(courier-pop3d daemon) shuts down the connection when the number of requests from the same ip address exceeds the predefined size. The default value for MAXPERIP parameter is only 4.
This can be seen in /var/log/mail.info on Ubuntu installs:
courier-pop3d: Maximum connection limit reached for [CLIENT IP]
Increase the max conn limit in confirg file: etc/courier-imap/pop3d
IMPORTANT, make sure you restart courier-pop3d daemon by this call to shell script:
This should be everything needed to resolve Outlook error 0x800CCC0F. Your email should work again :)