From 'man Net::POP3':

[login]
   Returns the number of messages in the mailbox. However if there are
+ no mes-
   sages on the server the string `"0E0"' will be returned. This is wi
+ll give
   a true value in a boolean context, but zero in a numeric context.

   If there was an error authenticating the user then undef will be re
+turned.
[download]

After Compline,
Zaxo