Hello :). You are missing a couple things:
-
MX Record for the public IP address of your exchange server
- Port 25 on your router needs to forward traffic to your exchange server
- You need to update your recipient policy in Exchange to include @domain.org as well as @domain.local. Make the @domain.org the default.
Do you need clarification on anything? You may also want to enable the Outlook Web Access feature and enforce SSL. That will mean forwarding port 443 to the Exchange server as well. This is for when users are off-site.