Repeatedly over the last few months I have issues with using POP with Yahoo. Normally this lasted a day or so, but usually cleared up. I have two accounts from which Outlook.com was pulling the mail but both stopped about two weeks ago with "We had an error retrieving your mail from..." I tried deleting and recreating one of the two but now I can't add it at all. It works if I add it as a sending only account so it can authenticate with the SMTP server only the POP server is giving errors. Yahoo claim there is nothing wrong at their end and I can POP it on the desktop, just not on Outlook.com. It's as if there is something in the POP logon which is giving an unexpected result.

Over TELNET the response is (user and password hidden)

+OK hello from popgate-0.8.0.450444 pop101.plus.mail.bf1.yahoo.com
USER XXXXX
+OK password required.
PASS PPPPP
+OK maildrop ready, 0 messages (0 octets) (0)

Which looks ok to me (although it doesn't show the username in the maildrop line)

Any ideas?