Consult with your network administrator, use a network analysis tool to see what goes over the wire and what connections are made. Maybe Mail::POP3Client has some hints on debugging?

Also consider the more verbose approach, also listed in the documentation:

...
  $pop2 = new Mail::POP3Client( HOST  => "pop3.otherdo.main" );
  $pop2->User( "somebody" );
  $pop2->Pass( "doublesecret" );
  $pop2->Connect() >= 0 || die $pop2->Message();
...
[download]

That way, you get more information from ->Mesage() maybe.

I strongly recommend you start reading the documentation of the module and follow the practices outlined there.