[Dovecot] plain authentication

[Roger D. Vargas]

After upgrading my server I have found that Im not able to use plain auth
for clients conecting from outside server. localhost clients (pine,
webmail) works fine, but if I use Thunderbird I got an error saying that
server requires TLS or SSL. But if I enable TLS or SSL I got more errors.
I have tried sevral combinations, but havent found a working one.

Here is my config, can somebody see what Im doing wrong?
# /etc/dovecot/dovecot.conf
protocols: imap pop3
ssl_disable: yes
ssl_cert_file: /etc/ssl/dovecot/server.pem
ssl_key_file: /etc/ssl/dovecot/server.key
login_dir: /var/run/dovecot/login
login_executable(default): /usr/libexec/dovecot/imap-login
login_executable(imap): /usr/libexec/dovecot/imap-login
login_executable(pop3): /usr/libexec/dovecot/pop3-login
login_greeting_capability(default): yes
login_greeting_capability(imap): yes
login_greeting_capability(pop3): no
mail_extra_groups: mail
mail_location: mbox:~/mail/:INBOX=/var/spool/mail/%u
mail_executable(default): /usr/libexec/dovecot/imap
mail_executable(imap): /usr/libexec/dovecot/imap
mail_executable(pop3): /usr/libexec/dovecot/pop3
mail_plugin_dir(default): /usr/lib/dovecot/imap
mail_plugin_dir(imap): /usr/lib/dovecot/imap
mail_plugin_dir(pop3): /usr/lib/dovecot/pop3
auth default:
  passdb:
    driver: shadow
  userdb:
    driver: passwd

-- 
Roger D. Vargas
http://dsgp.blogspot.com