[exim] Router/Transport Problem with multiple entries

Hi folks,

I have a niggle. I use the router and transport shown at the bottom.
With this setup I have one case where mail does not get delivered. It
sits in the queue and delivery errors fail with "remote_smtp_smart
transport has empty hosts setting"

Say I have the following in /etc/staticroutes

domain1.com: 1.1.1.1
domain2.com: 2.2.2.2
domain3.com: 1.1.1.1

Delivery to each domain individually is fine. A message addressed to
user@??? and user@??? is fine.

A message which contains any user at domain1.com and domain3.com will
fail as both domains point to the same IP address. Can anyone see an
obvious reason why these would fail?

Thanks.

#Router

static_route:
driver = manualroute
transport = remote_smtp_smart
route_data = ${lookup{$domain}lsearch{/etc/staticroutes}}


#Transport

remote_smtp_smart:
driver = smtp
port = 25
delay_after_cutoff = false
hosts = ${lookup{$domain}lsearch{/etc/staticroutes}}
hosts_override