I think you might have mis-understood Yahoos stance on POP mail.
"POP Access to External Mail:"
<You can configure Yahoo! Mail to retrieve messages from most External Mail accounts to which you have POP access. An account with POP access is one that you are able to access through an external email client such as Outlook, Eudora, or Netscape Mail.
In otherwords, if you have an account on a POP server, Yahoo can retrieve it. Yahhoo is not a POP server (http). It might have changed since I had a Yahoo acct., but I'm thinking it's still the same.