If the proxies contained in the source are for some reason unsuitable for the execution of the project or the source itself is not trustworthy, and ZennoProxyChecker continues to add and check proxies from these sources, wasting precious time and resources, then such a source can be added to the Black list and You won't hear from it again.
How to set up a blacklist
To create the Black list, go to the Sources tab.
To add several sources to the Black List, select them in the list of sources and activate the Add to Black List item in the context menu.
When adding sources to the Black List, proxies added from these sources are removed from the proxy base.