[exim] route_list for smarthost

Hi,

I'm reviewing the configuration of a smarthost router. I want all mail from
the local host to be routed through our mail cluster.

The cluster has three servers, which I can either list separately like
mx1.sussex.ac.uk:mx2.sussex.ac.uk:mx3.sussex.ac.uk or through a round robin
lookup, smtp.sussex.ac.uk

The servers are configured with failover, so in theory the IP addresses are
available all the time. However, there is a gap in availability - of a few
seconds - during failover and failback. During this gap, I want to avoid
mail sticking on the localhost.

So, my question is this. If I continue to use just "smtp.sussex.ac.uk",
will Exim try to deliver the email to all three IP addresses before
queueing the outbound email? Or, do I need to use the explicit list of
three hostnames?

--
Ian Eiloart
IT Services, University of Sussex