[exim] relaying listener concurrently with incoming mail lis…

Greetings on the list,

I'd like to make a configuration with exim:

1st instance should be a listener to port 25 which accepts
    all incoming mails and interprets all local domains.
    Port 25 connections should be only accepted from the
    upstream ISP mail exchange by IP filtering tables.

2nd instance should be a listener to port 2525 (or something non-standard)
    and allow my local Thunderbird clients to inject mails after
    doing some STARTTLS authentication to be able to relay mails
    to the internet.

Is there a configuration example describing this scenario already?

Greetings
-Achim