Exchange 5.5 IMS SMTP re-routing broken

Hi All,

I have a problem that is driving me up a wall. I’m trying to allow a ColdFusion server to send mail through our Exchange server via IMS re-routing and it’s not working. Here are the settings:
1) SMTP traffic is allowed (verified)
2) I checked the re-route incoming SMTP mail option
3) There are 3 domains routing to and that is working
4) Under Routing Restrictions, I checked the box “Hosts and clients with these IP addresses” and added the IP address of the ColdFusion server with a Mask of 255.255.255.255

When I try to send an email from the ColdFusion server to an external address, I get the following message: SMTP server replied “Mailbox unavailable.”

PLEASE help before I throw this thing out the window.

THANKS!!!
Martin