[exim] exim as forced tls client

Hi

I want to configure exim in such a way, that whenever a verification callout
or delivery for a special domain is initiated, it shall connect to a host
with ssl only and issue smtp commands over that line.

Basically my problem is:
- how to configure exim to connect to a server with ssl/tls ONLY ?
- how to configure exim to use a special cert? (not only accept whatever the
server gives me)

BTW: This is my idea to work around a ETRN problem: After a etrn command is
send, the client might disconnect their dial-up connection and another user
might get their ip. Then mails would be delivered to the wrong host. This is
inacceptable. Furthermore etrn would not allow callout verification.

Regards,
Steffen