[exim] fallback smart hosts

Hello,

Is it possible to configure a fallback smart host in exim4? I found
information about setting fallback hosts in case that delivery failed,
but that's not really what I am searching for.

My exim4 mta always uses a smart host (with SMTP AUTH) for sending mail,
and I would like to configure one or more fallback smart hosts in case
that the primary smart host that I currently use is not available.

greetings,
jonas