I have installed Postfix.
Postfix was configured. I can telnet to Postfix. Postfix is accepting mail correctly from the outside world.

I have installed Courier-IMAP.
Courier-IMAP configuration has been left default. I can telnet to Courier-IMAP.

I have created a UNIX user account (user name: lol) (password: 11).

I am using Thunderbird as my mail client. Thunderbird can see both SMTP (Postfix) and IMAP (Courier-IMAP) servers. I am using the user name "lol" and password "11" to login - the problem is that Thunderbird is saying I have the wrong user name and password.

I have tried logging in via Telnet, and this is what I get:
telnet localhost 143
Trying ::1...
Connected to localhost.
Escape character is '^]'.
* OK [CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE ACL ACL2=UNION] Courier-IMAP ready. Copyright 1998-2008 Double Precision, Inc. See COPYING for distribution information.
AB LOGIN "lol" "11"
* BYE [ALERT] Fatal error: No such file or directory: No such file or directory
Connection closed by foreign host.
What have I done wrong?