imap erro

alguem tem alguma ideia desse erro ai do imap?

[root@mail ~]# telnet 10.77.4.154 143
Trying 10.77.4.154...
Connected to 10.77.4.154 (10.77.4.154).
Escape character is '^]'.
* OK Dovecot ready.
user assis
user BAD Error in IMAP command received by server.