[exim] is there a way to prevent host based defer...

I have been searching the FAQ and the archive and decided it was time to
post to the group.

Here is the situation: I am using Exim 4.63 on RHES. We send all our
outbound mail to a third party external system which is load balanced
and geographically dispersed.

The Exim daemon is set to start a queue runner every minute (exim -bd
-q1m)

In my config I am also using the following:

queue_smtp_domains = *
split_spool_directory
queue_run_max = 10
remote_max_parallel = 1


And my last router looks like this:

# The following router will send to remote smart host
send_to_remote_smart_host:
driver = manualroute
domains = ! +internal_domains
transport = remote_smtp
ignore_target_hosts = 0.0.0.0 : 127.0.0.0/8
route_list = * remote.smart.host
no_more

recently, we have had delays when sending to certain resolved host IP's
on the third party system. When that happens I start to see a backup in
the queue with several messages showing up as deferred in the queue.
Many times the initial problem is with a message with a large
attachment, but all the other messages that were deferred seem to stay
on the queue skipping retry as long as the original offending message is
still unsent - and that seems to be the only message that is retried.

What I am assuming is happening, is that Exim is deferring all other
messages that it determined were bound for the same host so they all go
into retry without having tried to deliver the message at all. Is there
a way to change that behavior?

Thanks,
Jeff