Change domain associated with the "admin" user

[fillos]

I have just had DA support set-up a FreeBSD box for me. The domain that was associated with the Admin user was domain.com, and I need it to be subdomain.domain.com. This would not be an issue, but I intend to host the primary domain name elsewhere, and I would like to be able to send mail to top level recipients on that server (ie me@domain.com). I would also like to be able to have a unique RDNS entry for each server that sends mail.
Is there a way (short of reinstalling the darn box) that I can associate subdomain.domain.com with the user, and get rid of the domain.com association altogether?

Thanks for any insights,

Mike

Edited for spelling

[fillos]

I scrolled down a little further in my search, and here the answer was.....
http://www.directadmin.com/forum/showthread.php?s=&threadid=1813&highlight=change+admin+domain

Thanks DirectAdmin Support