Prevent Smart Hosting for Local Domains

[nmnadmin]

I'm somewhat stumped. Due to an issue with my IP range I am currently smart-hosting all mail via a remote relay server. However, I have noticed that for some reason local domains are also send through this relay server. Why would that be and how can I prevent this from happening? (Using 9.78 on Windows 2012 server)

[Admin]

So all emails to local mailboxes are being sent out and not delivered locally? Possibly if you have used the MERoute utility this could happen, but you should be able to check by running the tracking utility in the administration program and following a message - the Debug logs would indicate why it is being sent out via SMTP. The MTA Debug log would be where to check.