The Domain Blacklist check runs once per day, checking your domain against nearly 100 well-known spam blacklists. If your website is included in any of these lists, the check will go “down” to alert you of the blacklisting.
This can be alarming, but is not a definitive statement about the security of your website. When a Domain Blacklist check fails, the full error message will report the specific blacklist on which the site was found. It is highly recommended to check with the blacklist organization that reported the message. Please note that if you are using a joint host it may be that an IP on this server may be the issue and not necessarily your DNS. Blacklist services such as Spamhaus offer tools to view detailed technical reasons why the site is included on the blacklist, which can be passed on to technical teams for further investigation.
Additionally, some blacklist services allow you to submit a request to have the site removed. If you do receive a spam blacklist alert, check with the reporting blacklist to determine next steps.
You can also reach out to firstname.lastname@example.org for more detailed information about the check and its down status.