please help this newbie get started

[drbobllc]

Hi, everyone,
I'm trying to get email working on a server. Web servers I have some experience 
with, but this is new for me.
On FreeBSD, with dovecot2 (2.2.27), when I try to check email, Thunderbird says:
Sending of password for user xxx did not succeed.Mail server xxxresponded: 
Authentication failed.
And on the server, in the mail log, there's a message:
dovecot: pop3-login: Disconnected (user disabled)
Any idea what I'm doing wrong? I didn't mean to disable any users. Thanks!
Bob