Networks

As long as your MX record for the second domain is pointing to the server:
1. Open Exchange System Manager
2. Click on Recipient Policies
3. On the Right hand side of the screen, right mouse click on "Default Policy" choose Properties
4. Click on "Email Addresses (Policy) Tab
5. Click on New, select SMTP address, then OK
6. In the address box, type @abc2.com (or whatever your second domain is)
7. Ensure "This Exchange organization is responsible for all mail delivery to this address"
8. Click OK, ensure your recently added address has a check mark next to it in the list
9. Click OK
10. Done!