The Essential Guide to Blacklisting

Being blacklisted is one of the biggest challenges a business can face. If your domain or IP address gets blacklisted, your emails are likely to be flagged as spam, which can prevent your communications from reaching customers or partners. This can severely damage your reputation and business operations. To help you avoid getting blacklisted, we’ve created this essential guide, covering everything you need to know about blacklists, how they work, and what you can do to prevent being blacklisted in the future.

What Is a Blacklist?

A blacklist, or blocklist, is a list that identifies domains or IP addresses that have been flagged for sending spam or engaging in malicious activity. These lists are maintained by security organizations to protect recipients from unwanted and harmful emails. It’s rare to end up on a blacklist without cause — it might be due to a compromised system, stolen user credentials, or even sending emails to a purchased prospect list.

How Does a Blacklist Work?

A blacklist works by preventing emails from being sent or received based on whether the sender’s IP or domain is included in the list. Email servers check the sender’s domain and/or IP against blacklists, which can result in emails being bounced or routed to spam folders. While some blacklists are strict, others may only flag suspicious emails for further review. The key is to prevent landing on a blacklist in the first place.

Who Owns a Blacklist?

Blacklists are owned and maintained by various security companies, such as Abusix. These companies create and manage the blacklists based on observed threats, security practices, and past incidents of abuse. Understanding how these lists are compiled can help you protect your domain or IP from being added to them.

Note: If you want to understand how Abusix’s lists are created, check out our blog post series here.

Real-World Scenarios That Can Get You Blacklisted

1. If you use shared hosting for email, a compromise of another account on the same server can cause your IP to be listed.
2. Infected devices within your network can lead to your external IP being blacklisted.
3. An email marketing campaign that exceeds your usual volume can trigger blacklisting.
4. If your cloud service provider reuses IP addresses, you might inherit blacklisting from previous customers.
5. A high number of spam complaints directed at your domain or IP will likely lead to blacklisting.
6. Compromised user accounts or web servers increase the risk of being blacklisted.
7. Vulnerable web forms on your site can be exploited to send spam, putting your server and IP at risk.
8. A high bounce rate for your email list signals non-opted-in recipients, increasing blacklisting chances.

How Do I Know If My IP or Domain Is on a Blacklist?

If your emails are bouncing back or ending up in spam folders, it’s a sign that your domain or IP might be on a blacklist. The bounce-back message will often contain diagnostic information about the issue. Additionally, you can use online tools to check if your domain, IP, or email address is blacklisted.

For example, you can use the Abusix Lookup tool to check whether your domain, IP, or email address appears on any of our blacklists. If you find a match, click the result to see detailed information about the listing and the steps needed to resolve the issue.

If the issue is resolved, you can request a delist by creating a free account on Abusix’s platform to remove your IP or domain from the blacklist.

Other Tools for Checking Blacklists

For a wider search, try MXToolbox or MultiRBL, which check multiple blacklists simultaneously.

Note: Blocklist maintainers don’t directly block senders; the email receivers who use these lists decide how they’ll handle the data. One receiver may fully block a blacklisted IP, while another may only flag it as suspicious.

How to Avoid Blacklists

Here are several strategies to prevent your domain or IP from being blacklisted:

1. Track Your Email Stats

Keep track of email opens, clicks, and bounce rates. A sudden drop in these metrics can indicate issues that need immediate attention. By monitoring these statistics, you can proactively identify and resolve problems before they escalate.

2. Communicate Spam Policies to Customers

Always get explicit consent from your customers to email them, using double opt-ins for email newsletters. This is not only vital for maintaining a good email reputation, but also required by GDPR and other anti-spam laws. Be transparent by publishing your privacy policies and spam rules on your website.

3. Verify New Customers

Verifying new customers can help prevent hackers from gaining access to your systems. Fake accounts are often created with stolen credentials, which can then be used to send spam. By using a verification process, you ensure that only legitimate customers are using your services.

4. Personalize Customer Emails

Personalized emails are less likely to be flagged as spam. A generic email is more likely to be reported by recipients. Segmenting your email list based on user interests and demographics can also help increase engagement and reduce complaints.

5. Protect Your Systems with the Right Technology

Using the right technology solutions, such as outbound email filters, firewalls, and encryption, will protect your system from unauthorized access and reduce the risk of being blacklisted. Implementing these security measures proactively will help you avoid the headaches of dealing with blacklists.

6. Stay Updated on Blacklists

Stay informed about blacklisting trends and monitor your network activity regularly. Reviewing security publications and subscribing to blacklist services will help you stay ahead of potential issues.

7. Use a Dedicated IP Address

Consider using a dedicated IP address for sending emails to prevent your email reputation from being affected by shared hosting or other users.

---

In conclusion, blacklisting can severely impact your business, but with proper monitoring and preventive measures, you can avoid the consequences. Regularly track your email statistics, communicate clearly with customers, and protect your systems to reduce the risk of being blacklisted. Blacklists aren’t going away, but with the right steps, you can stay protected.

If you want to safeguard your email network, try Abusix Mail Intelligence for a free trial to prevent malicious email-related attacks and keep your servers safe.