OK, here's the scoop - I've got a system running with a couple of domains on it. RedHat 7.1, sendmail 8.11.2-14, Apache, DNS, et all. Everything is running smoothly. This box has the localhost set to my first domain name, and no localdomain specified.

I'm upgrading (replacing) the system, and would like to do this without actually shutting the first system off until the second one is online and ready to go. I should note at this point that I took the easy way out when I set this up in the first place - I'm running an OvisLink router. This make directing traffic to an IP easy, so I can get applications running one at a time....

Now, the second system.... I've set an alias for the localhost, and set the local domain to the domain name (localhost) of the first system. When I first attempted to name the original system whatever.mydomain.com, I lost all communications outside the local network (this is why I used the domain name for the localhost name, it worked).

So, now we're down to the issue.... I'm getting ready to start directing the traffic through the router to the IP of the new system, and I already know I'm going to have problems with due to the way I've specified the localhost and localdomain names. I've gone through tons of documentation, and have been unable to find whatever it is that I'm missing. A quick sendmail test results in an error stating that the domain of the sender does not exist. It simply does not like an alias in front of the domain name...

What *AM* I missing?