[exim] Exim configuration

Hello exim-users,

I have a FreeBSD box running Exim-4.43 as mail server for my company.
There are several filtering tools running on my mail gateway. All
users are using POP3 client to read their e-mails.

Now I need to set up Lotus Domino server inside our LAN and I'll have
to move several users into Lotus. I'd like to leave my SMTP gateway
running Exim for mail filtering and use Domino server inside LAN for
final mail delivery and documents exchange. Moreover several users
must have their POP3 accounts on the mail gateway.

How can I implement this configuration? I've read the "Smart host"
section of Exim's documentation and still have no idea. It's not so
clear for me how to set up selective transport, which would be able to
route mail for user1, user2 ... user5 to the internal Domino server
and to deliver mail for user6 ... userN into local mailboxes.

Thank you in advance for help!

--
Best regards,
Timur Nasyrov