We have set up a new SMG service, one controller and 6 scanners, all virtual edition, in what is technically a DMZ (we are an ISP and filter mail for our clients as well as ourselves).
I have set up numerous local domains, and set optional forwarding on all these to the client smart hosts (e.g. mail.company.co.uk). For the majority of the domains, this works fine, except for our own domains.
For all our clients, I am able to telnet from any of the scanners to their smarthost names (all Exchange servers). The issue is when I attempt to connect to our internal Mail server, I get a connection refused error. I have successfully been able to telnet from Windows servers in the same subnet to our Exchange server, the issue is with the SMG servers. Firewall rules have been created to allow the traffic, and the Exchange server shouldn't be dropping these connections.
Are there any settings I can check on the scanners? This problem is really confusing me as to why it's working for some, but not all of our smart hosts.
Please help