According to Raymond J. Henry:
Can anyone point me towards documentation for running majordomo on multiple domains that's written for real idiots? I've blundered through all the documentation I've found, and was unable to make it work. I've always given up in the past, but now I think I'd really like to get it going...
My RedHat 7.1 box has a handful of domains and virtual domains that I'd like the option of getting majordomo to work on for each domain/virtual domain that reflect the correct domain name.
I just did a Google search on "majordomo" and "virtual domains" and this came up at the top of the list...
http://www.linux-consulting.com/FAQ_virtual/Virtual.gwif.html
Not a lot of detail to the documentation, but the example files they provide will hopefully help you in your setup.