I'm following this howto which has been reallu usefull. http://msexchange.org/tutorials/MF002.html My question is - The company I'm setting this up for uses multiple domain names. What steps would I have to change or add to allow the exchange server to put the email in the right container. All users have a default email of xxx.com but some have yyy.com as well as xxx.com and other have zzz.com ontop of all of that. And all I have to do is open port 25 tcp on the firewall to point to the local ip of the exchange server right?