POP3 netcat protocol error

Question

I tried to connect to my POP3 school server as part of my assignment. Now, I can connect to the server but the real problem is when I try to log in using the "USER" command.

c:/>nc server.pop3.com 110
+OK Microsoft Exchange Server 2003 POP3 server version 6.5.7638.1 (server.pop3.com) ready.
USER myuserid
-ERR Protocol error

Now I'm wondering whether there's an issue on my side or on the server? Thank you for the time and answers.

Answer 1

Use CAPA command just after connection.

You'll see what login mechanisms are supported.

Exchange usually does not allow clear text mechanisms. Most likely you'll be forced to use SSL+plain text, or APOP login mechanism.