[Exim] load balancing on out going mail ?

Does Exim have any features that would allow me to do load balancing on an
outgoing message, by alternately sending portions to different smartuser
hosts, as listed in some sort of host list or file.

That is, if I had a message going to 100,000 recipients, I would want to
send the first 100 (max_rcpt) addresses to HOSTA, the second 100 to HOSTB,
the third 100 to HOSTC, etc. etc. and then cycle back to the first host in
a list, until all receipents had been sent to the smarthost for delivery.

This is similiar to fallback_hosts, or hosts in the transport, or the
route_list in the domainlist section.

Thanks for any clues on solving this problem.

mark