mail server question

I've been setting up an email server for test purposes. It's running on Centos6. It's using postfix for smtp and dovecot for the mailbox server. I have tried to set up an email account using Thunderbird trying several accounts (root and my normal user account) but I keep getting invalid username/password. I'll post configs if needed.

When I try to connect via telnet I get "Connection closed by foreign host."