please help this newbie get started

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