APOP (aka "secure password") fails in Entourage X. Help?

[John Lubotsky]

I want to require apop authentication on my pop server, which it
supports. Connecting via Eudora, no problem. Connecting via Entourage
without checking "always use secure password", no problem. Connecting
via Entourage with "always use secure password" checked, Problem. I
get an error 7010: "Command not implemented. Check the
username/password or security settings."

I've scoured the Web and the docs, no love. Help?

Best,
John