I think your friend is able to Use outlook express which is on the server he is connected to, Are you sure it is Installed on your friends compter.
I've not heard of anyone that has INSTALL outlook express on there system running windows 7.
Myself, I use Outlook which is bundled with the higher end Microsoft office.
I did Install Vista WinMail (Outlook express replacement) on to My wifes windows 7 system, But that is NOT a simple download and install.