Ehh, nevermind, now all of a sudden this is working. I just changed the
field "from" in the database to "from_address" to avoid having to type
it out as `from` since that is a reserved word... Not sure why that
would have effected Exim being able to populate the $sender_address but
that's all I changed. Oh well!
from_based_routing:
driver = manualroute
domains = !+local_domains
transport = remote_smtp
route_data = ${lookup mysql{select smarthost from routing_table where
from_address=\"${quote_mysql:$sender_address}\"}
