Hello All, In my lab environment, I am testing smtp connectivity between two different exchange 2010 organizations. They seem to work when Smart Host is used on both sides, but are unable to resolve each other through DNS. Since they are both on LAN, I used the DNS on both organizations to find each by creating a zone of each in others DNS and then by providing MX record pointing to the respective SMTP Server. Like abc.com active directory DNS has xyz.com primary zone as well and similarly xyz.com active directory DNS has abc.com primary zone as well with MX records defined. But, still I get DNS resolution error on both SMTP servers? When I do nslookup, it shows localhost as the host for MX Record and not the IP Address of the MX Record's A record. I assume this is what causing the problem, but MX records are defined correctly. Yet the NSLOOKUP shows localhost on DNS Servers. One of the Exchange is on DC so that is understable, but the one that is not on DC also shows localhost. So I am not sure how to get around this.