With Control Panel version 6.35.8.0, two additional whitelist entries have become necessary for new installations or updates of already installed add-ins.

The following two domains must be enabled in the firewall for port 443, so that the Phishing Reporter add-in can work without problems:

services.cp.hornetsecurity.com

services.cp.cloud-security.net

Here you can find the other whitelist entries for the firewall.