[exim] Exim TLS - problem

Hi,

I have easy question. How to force TLS connection before SMTP
authentication in global exim4.conf?

I have following settings for TLS:

tls_certificate = /etc/exim4/srv.pem
tls_privatekey = /etc/exim4/srv.pem
tls_advertise_hosts = *

This is allow to send messages with TLS, but without TLS too. (example;
"never" TLS option in Thunderbird SMTP settings).

When I set in my exim4.conf:

auth_advertise_hosts = ${if eq{$tls_cipher}{}{}{*}}

and mark "never" TLS option (Thunderbird) for testing message is sent
without asking for my password (password window isn't displayed at all).

When I mark "TLS" option it works correctly.

I to define tls_require_ciphers option too?

Help me please.
Regards

Slawek