[exim] Routing email to different smarthosts accordin to a …

Hi all,
I have been using exim for a long time but it is my first time that I am posting here

I am writing to ask for any suggestion in relation to this

Let say I have 3 smarthosts: smarthost0, smarthost1, smarthost2

Smarthost0 receives all the emails and then routes, let say, the 10 percent of the emails via smarthost1 and the 90 percent via smarthost2

There is a way to do this with exim?

I would like to implement something like this as a way to warm up/or keep warm an IP

Anyone's got an idea?

Cheers,
Diego