[Pkg-exim4-users] 2 out smarthosts 1 local 1 internet

[hput]

Setup:
ubuntu-22.04
running LXDE desktop.
Installed exim4 (4.95 I think)
-------       -------       -------

I currently have no mta working on any machine

A bit confused on the questions asked during initial setup:
with   sudo dpkg-reconfigure exim4-config

At the point it asks about a Smarthost:

My setup is a home network with several machines on one network.

I want to setup exim4 to act as smarthost on one of them.
So all it would be hosting is 4 other machines on same subnet.

But, I still have to send what ever is going out to a `real' smarthost
on the internet that I have creds to send thru.

I'm guessing the smart host I'm being questioned about should be my
internet smtp server.

But will putting an internet smtp server in the questionnaire
. . result in having a serious problem setting one local machine to
receive mail from home network and send it on to smtp inernet server?

Should I go ahead and setup for the internet smtp server and worry the
about local part afterward?