IP address and domain blacklists
This article covers email IP address blacklists and how they can affect the effectiveness of your email campaigns. This includes identifying the most common blacklists, the steps required to delist your IP address from them, and more.
Email IP address blacklists, also known as DNS-based Blackhole Lists (DNSBLs) or Real-time Blackhole Lists (RBLs), are databases of IP addresses that have been reported or identified as sources of spam or other malicious activities. These lists are used by email servers and spam filters to block or filter out emails from known spammers.
Public blacklists
Many popular email IP address blacklists exist, such as Spamhaus or SURBL (Spam URI Real-time Blocklists), and most of them operate independently of one another. If an IP address or domain are listed in public blacklists, you can look it up through public services like mxtoolbox.com.
View the most popular email IP address blacklists in the table below.
Name | Check listing | Delisting information |
SURBL does not have a direct lookup tool. Check with your email security software or service for implementation details. | Delisting instructions might vary depending on the particular SURBL implementation. | |
The impact of being listed on a particular blacklist can vary, and many mail servers use a combination of multiple blacklists for spam filtering. If you address issues that led to blacklisting on one service, this might also positively impact email delivery across other platforms. Additionally, understanding the specific filtering policies of the email service providers and implementing best practices for email security can help prevent future listings on popular blacklists.
Non-public blacklists
Many email security companies and services operate their own internal threat intelligence, spam filters, and blacklists without necessarily maintaining public DNS-based Blackhole Lists (DNSBLs). These internal mechanisms are designed to detect and block email threats, spam, or malicious activity. The only way to know that the IP address is listed in this type of blacklist is to check the server logs of Creatio Bounce Monitor for rejection messages.
Here are a few examples of companies known for providing email security services that may not operate public DNSBLs but offer robust spam filtering and blacklisting capabilities:
- Symantec (part of Broadcom).
- Talos (part of Cisco Email Security).
- Trend Micro Email Security.
- McAfee Email Protection.
- Forcepoint Email Security.
- Proofpoint.
- Xfinity.
- Cloudfare.
Tools for checking an IP address or domain in blacklists
These tools contain lists of the most popular blacklists. They serve as a scanner across all publicly available databases. To use them, enter the IP address or domain and wait for results.
Delist IP addresses
To delist your IP address from a blacklist, follow these general steps:
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Identify the blacklist. Determine on which blacklist(s) your IP address is listed. You can use online tools like MxToolbox or check our Bounce Monitor server logs for rejection messages.
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Investigate the cause. Identify and resolve the issues that led to your IP address being blacklisted. This might involve stopping spam or securing your mail server against abuse.
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Contact the Blacklist Operator. Visit the website of the blacklist operator and follow their delisting procedures. This often involves filling out a delisting request form and providing information about the steps you have taken to address the issue.
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Monitor Progress. Some blacklist operators provide tools to check the status of your delisting request. Monitor the progress and follow up if necessary.
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Prevent Future Listings. Take steps to prevent your IP address from being relisted. This might involve implementing strong security measures, using authentication mechanisms like SPF and DKIM, and monitoring your email traffic for signs of abuse.
The delisting process can vary among different blacklist operators. Make sure to follow the instructions provided by each blacklist carefully to improve your chances of successful delisting. Additionally, maintaining good email practices and securing your server against abuse is crucial for preventing future listings on these blacklists.