Same problem, but my server IS responding on port 17001
Setup
Frontend Server IIS6 running on Windows Server 2003 Webedition.
Backend Server Smartermail v.4.0.2592
I copied the MRS folder to my frontend IIS webserver and created a website pointing to that folder.
I edited the Web.config <add key="MailServiceAddress" value="IPC"/> to <add key="MailServiceAddress" value="BACKENDSERVERIP"/>
I checked out the official post to see if the Backend Server was listening to port 17001 - IT IS
I ran PortQueryUI (From Microsoft) from the Frontend Server and the Backend Server is listening on port 17001
I still get the Unable to connect to SmarterMail Service.
This was working just fine in Smartermail 3.X
I'm running SmarterMail Enterprise version.
(I opened a Ticket - earlier today) I'll report back if I get anything