pop3 error

Hi,
Ive installed qmail on my FC4 system. Using thunderbird am my MUA, im=20
able to send messages after authenticating, but while authenticating for=20
pop, im shown an error

sending of password did not succeed. Mail server 127.0.0.1 responded:=20
authorization failed, but when I use /bin/checkpassword from CLI, its=20
working fine.

Please advise

Danish
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