Usenet providers such as Fast Usenet offer SSL/TLS security. The official network protocol is called NNTPS (Network News Transfer Protocol Secure) or NNTP (Network News Transfer Protocol). Similar to HTTPS for websites, NNTPS serves two functions.
There are many Usenet providers that offer NNTPS but only a select few have verified certificates working correctly. The new default setting in SABnzbd version 2.0 defaults to strict SSL mode. What strict SSL mode does is checks to make sure the server name matches the server address. For example when you connect to secure.fastusenet.org the installed certificate on our server matches that address. This allows SABnzbd and other newsreaders to verify it's connecting to the correct server and offers additional security to users.
Below is an example of how the error will appear in SABnzbd if the SSL certificate doesn't match the connecting host name. We've blurred the actual host name information in the example.