Testing email

New RT install 388 on FreeBSD8
I’ve got my RT web up un buzzin and mail works in and out of the BSD I am setup on.
I now need to simulate a real email service without an internet connection, to whip up interest in getting RT live or I am dead.
What does the list recommend to have in the Windows world to simulate RT working in a real world network.
I am actually running - Suns VirtualBox in XP/Vista hosting FreeBSD8 guest and all works fine.
Do the RT testers use some setup that would do this ?