I followed your guide à-la-lettre :
Though, I have this problem while getting my email :
+OK Password required.
-ERR chdir ar-systems.net/arthur/ failed
Connection closed by foreign host.
I made things exactly as you said, and syslog returns me this :
Jun 18 11:57:31 stock courierpop3login: Connection, ip=[::ffff:127.0.0.1]
Jun 18 11:57:44 stock courierpop3login: chdir ar-systems.net/arthur/: No such file or directory