I've read through this site for about three days but I'm not getting something right. Here is the layout, please feel free to ask for more details if needed...
Internal Domain: domain.loc
Primary exchange: @company.com (working correctly)
MX for primary: 10.9.8.7 (example only)
example address: firstname.lastname@example.org
Secondary email address for only 3 users: @business.com (works and one person has multiple email addresses)
MX for secondary: 10.9.8.7 (example only)
example address: email@example.com, same person has firstname.lastname@example.org (all work)
ISSUES STARTS HERE: Our owner had his own exchange server but due to security issues he wanted it moved to our main location. Instead of having to keep his box (which only forwarded to our box) we want to move his domain email to our corporate exchange server.
Pointed his MX to: 10.9.8.7
His domain: @personal.com
I've gone into his domain account, mine and his assistant and added email@example.com.
When I send from Outlook INSIDE the company everything works fine. If I use an external account such as Yahoo or Gmail I get the error:
Sorry, we were unable to deliver your message to the following address.
Remote host said: 550 5.7.1 Unable to relay for <firstname.lastname@example.org> [RCPT_TO]
I've scoured my internal DNS and exchange to see how the business.com domain works and the personal.com domain does not. I see no differences and I'm getting nervous calls from the owner.