We just recently updated to the RC1 release of Team Foundation Server and I had to reconfigure the e-mail settings on the server. I had to do this the first time as well when we installed the Beta 3 Refresh version.
I didn't take part in the actual installation process so I don't know if the install asks for the SMTP server and Reply To address and the person installing it for us just didn't enter it, or if it's just not part of the setup.
In any case, if you ever need to go back and change the e-mail (SMTP) server or Reply To address, you can do it by editing the Web.config file under the following web service folder:
C:\Program Files\Microsoft Visual Studio 2005 Team Foundation Server\Web Services\Services
Note that your installation folder could be different.
The SMTP server is configured by the "smtpServer" key/value pair under appSettings and the Reply To address is configured by the "emailNotificationFromAddress" key/value pair.