How does IP Address or Domain blacklist work?

A blacklist is a list of IP addresses or domains that are known sources of spam. Often referred to as DNSBLs (Domain Name System Blacklists). The technology is built on top of DNS. Most MTAs can be configured to reject or flag messages that have been sent from a blacklisted IP. In this article, you will learn about how IP Address or Domain blacklist work. Please see How To Configure a Domain Password Policy, How to Set a Static IP Address in Windows 11, and how to add a new Domain Controller to an Existing Domain.

When a specific domain or IP is blacklisted internally. There is a possibility that this is propagated to a third-party blocklist (blacklist).

Please see What to note before assigning Multiple IPs’ to an Instance, how to “Perform Office Online Server Update via the Microsoft Update Catalog“, and how to Create a web page to visualize the output of BitLocker Script.

What happens when an IP is blacklisted?

This record takes time to update and can take up to 48 hours. As soon as you have removed the IP (domain) internally. The third blocklist (the record still needs to be updated, and this can take some time to update).

Note: Many mail servers work this way (e.g., Exchange Online Protection).

I hope you found this blog post on how does IP Address or Domain blacklist work? helpful. If you have any questions, please let me know in the comment session.