First off, this forum is mainly populated by Customers like your self. The admins only come by once in a while.
You can put in a sigguestion (Panel > Home > Sigguestions) for this.
Also for the most part you can install software your self, as long as it’s not a presistant process. I know other people have installed web-mail software, and the only draw back is that you have to log in with the mxxxx name.
Have you searched the Wiki and this forum to see if anyone else has allready installed them?