Configure relay inbound messages to non-local recipients

Hi!

I need some help about how to configure the scenario below:

I have SMG ver.10.0.1-2 for inbound mail filtering only.

I have 2 external web servers who sends emails with my mail domain to non-local domain recipients.

My idea, if is possible, is configure the SMG with some rule that accept inbound mails from the IPs of external web servers, and redirect to my internal exchange server, from where this messages will be sended to the recipients.

At this moment when I try it, SMG reject the message with this action error:

All recipients are invalid. Message rejected for non-local recipient.

Is my idea possible? Please could somebody help me?

Thanks in advance!