I’ve just tried the anti-phishing test here http://www.amtso.org/check-desktop-phishing. The page loads, so it seems that, according to the page, “Avast fails as If you can read this page, it indicates either: Your Anti-Malware solution is not (yet) supporting this Feature Settings Check, or Your Anti-Malware solution’s Anti-Phishing feature is not enabled or misconfigured.”
As far as I can see, there is nothing I can set up which isn’t already, so I’d be grateful for confirmation that Avast is not enabled for this.