We are currently running exchange 2010 in a dag environment consisting of 3 mailbox and 4 cas/hub servers. we are currently host 10 email domains and all our external emails go through a smart host connecting to an external spam filter.
our company abcd.com bought a company xyz.com, 3 months ago. In order for the employees at xyz to be able to use abcd email addresses. We created contacts for them i.e. firstname.lastname@example.org forwards to email@example.com.
All of these contacts are routing through the smart host that connects to the external spam filter.
They want me to look into seperating the xyz users to be able to send emails using dns instead of using the smart connector.
Problem is I need to make sure all of the other users at abcd are able to route emails using the smart connector since they use the same email domain abcd.com
we also have a site to site link with them now. they are also running exchange 2010 on their end.
Is there a way to route email using a specific OU or creating a federation trust will help in this matter.