I have two locations using two different domains for mail (lets call the US exchange "us.mycompany.com" and Ireland location "mycompany.com"). An Exchange server resides at both locations. Both have public MX records that point to each server in its respective country. Currently if someone wants to send an email to US users they append the "us.mycompany.com" and if they want to send to the Ireland users they append "mycompany.com". The reason why we have an email server at both locations with two domains is because the VPN link between the offices is slow.
What I want to do is use one domain mycompany.com. However, when the email gets send to Ireland email server, is there a way to tell it to send it to the other Exchange server via IP address. I dont want the mail to be sent through the VPN link but rather to go back out to the internet to a public IP which will correspond to the other Email server.
Also is there a way to preference email servers such as if anyone in the US sends to mycompany.com, it doesnt have to go to Ireland, but will find a server in the US to deliver the mail. I know you can set preferences on MX records, but can you set them based on where the mail is coming from? \