Whenever I have tried to use balsa I have never been able to get it to function correctly. Try sylpheed would be the easiest to install on RH 7.1. Kmail is pretty nice,if you had KDE installed. I used it for a long time until Evolution came out. Evolution is what I use now, but it would be a project for you to try and install it on 7.1. It would require an upgrade to Gnome 1.4 on 7.1. It requires the addition of quite a few rpms just to install it on 7.2. I expect Evolution will replace balsa as the default Gnome e-mail client in the next version of Red Hat.
I think I forgot something. :
I would try this rpm