I can see the "contact group-owner" button, but when I click it my computer asks me to configure that email-program that I never use. That is very unpractical. If I'm using webmail, especially when I'm on someone else's computer, I want to send messages from my webmail.
That's a setting in your browser. You need to set it to whatever your default email is. Or, change your PC's default email setting to your webmail.
