I found a solution to that same problem that may work for others;
I have a free email account with Yahoo.com - this account would not let you
"POP" mail to email programs such as Outlook. After searching in Yahoo help
I read about the different free vs paid email accounts. So I paid the $19.95
for the Yahoo "Plus" account and it took 15 minutes for the account to switch
over. The mail started rolling into Outlook instantly when I opened the
program. I assume this will now work in Mac Mail program as well.
So there you have it - at least at in Yahoo you must pay for your email to
be able to pop it to another program.