There is an app that I used called MailMan for web-based email. I'm sure that you can take the script and modify it as needed.
I believe it was at
http://www.justasp.net
Okay, forget that. I just tested the link and it no longer is there. I have a copy at
http://www.xsol.net/scripts/mailman.zip so you can get it there
this link so you can grab it. It is freeware as far as I remember
