The website is operated by a private person. The law however is pretty clear that a company needs to accept a signed notice of termination in any form and a cou

The website is operated by a private person. The law however is pretty clear that a company needs to accept a signed notice of termination in any form and a court ruled that accepting that email works and nobody actually needs to read that email, the SMTP receipt works. So what that website does is it collects email addresses for companies and support systems, provides a template and lets you sign with the Austrian digital signature (or just a scribble on the screen). Then it sends it for you. If they don't respond they follow up automatically and tell you how to automatically file a complaint with the regulator. I have been cancelling a lot of services this way and never had an issue.