I have a server running CentOS 5, with DirectAdmin running on that server. I need to have email FROM certain domains be routed through a smart host, that host being a mail server for the Reflexion spam filtering service. However, not all of my customers have signed up for this service; out of hundreds of domains, only five are active in the spam filtering service.

I found a way to send all outbound mail through that server, but it rejects the relaying of any mail from a domain not enrolled in the service or otherwise allowed from within the web interface. How do I tell the mail server to only route mail originating from these domains through reflexion? I've created a list:
domainlist reflexion_domains = (list of domains separated by semicolons)

And added this section to the routers:

# This router routes mail from domains associated with Reflexion through the Reflexion server. (not working)

smart_route:
driver = manualroute
domains = ! +local_domains
transport = remote_smtp
route_list = * asp-submit.reflexion.net

When I change the domains line to:

domains = +reflexion_domains

it ignores it; which makes sense, since I got that from a method for routing by the destination domain, not the sending domain. I also tried altering the last line:

route_list = +reflexion_domains asp-submit.reflexion.net

And it also seemed as though no email went out. I'm sure there must be a way to do this, but I'm not having any success finding it on my own.