What Is Email Blacklisting and How to Avoid Being Blacklisted

BySuryanarayan Pal


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In today's digital era, email marketing is the secret ingredient to a business's success. However, brands can lose 20% of their earning opportunities if their email fails to reach the recipient's mailbox. As a result, all your email marketing efforts can go in vain.

Email blacklisting is the main reason why your marketing emails end up in the user's spam folder. That means you are not ending up in your subscriber's inbox. Let's understand what email blacklisting is and how to avoid it using various tactics.

Table of contents

What is an email blacklist?

An email blacklist or DNSBL (Domain Name System-based Blackhole List) is a list of those domain names or IP addresses that are associated with suspicious or spam content from untrustworthy sources. It is essentially a real-time database, therefore also known as RBL (Real-time Blackhole List).

The email blacklists aim to prevent unwanted spam content from reaching users. Mailbox Providers such as Gmail, Yahoo, and much more use these blacklists as a filtering mechanism for detecting and blocking spam emails. Likewise, Internet Service Providers (ISP) and Anti-Spam Agencies (ASA) also refer to these blacklists.

The email blacklisting practice can adversely affect email marketing campaigns. Being put on a blacklist can cost a lot to a company as it can drop their entire email deliverability rate. When a brand's domain name or IP address is blacklisted, its emails end up in the user's spam folder instead of inbox. Let's have a quick look at who maintains the email blacklists and how you can avoid getting on one.

Who maintains the email blacklist?

There are three types of email blacklists that are maintained -

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1. Public blacklists

The public blacklists are directly available for all. Anyone can check these blacklists through different tools.

2. Private blacklists

The mailbox providers such as Gmail and Yahoo maintain their private blacklists database. Major mailbox providers use these internal lists to filter spam. And, you require a license to check the internal blacklists. One cannot access their private blacklists directly. As a result, email marketers can only monitor the server logs to check if their IP address is blacklisted or not.

3. Enterprise spam firewalls

Apart from the public and private blacklists, some independent organizations maintain and provide blacklists. For example, Barracuda, McAfee, and other renowned companies keep records of spam domains/addresses. Corporate IT departments primarily use these blacklists or firewalls as a security mechanism. Even Gmail and other known mailbox providers depend upon these third-party services alongside their database.

The most popular blacklists available online are:

Why do you become blacklisted?

It has been observed that companies often land up being blacklisted despite the best technical software and practices. Some of the reasons for blacklisting could be:

1. A huge number of spam complaints

ISPs and email service providers tend to blacklist your address if your recipients mark your emails as spam. In this, the unsubscribe opt-in can help filter out the uninterested recipients, thus reducing the spam complaints from their end.

2. Bad email lists

Poor email list hygiene can lead your business to get blacklisted. You must be careful while preparing the email list. It's better to use reliable email marketing software with which you could monitor the performance and refine your email lists whenever necessary. An updated email list goes a long way rather than a stale one.

3. Spam traps

ISPs use spam traps to track the spam IP addresses. There are three types of spam traps, recycled spam traps, new spam traps, and typo spam traps. These spam traps critically act as fraud management tools. Based on the evaluation of which, ISPs decide whether to blacklist your IP address or not.

4. Hackers

If hackers got access, they might also spoil your senders' reputation by sending spam emails. You can check this through the error messages you receive on account of the emails you did not send.

5. Malware infection

At times, your system is infected with different malware such as Virus, Spambot, and Trojan. Emails sent through the infected systems will not pass the spam filters, thereby not reach the desired destination. Running antimalware checks at regular intervals can help the marketers in maintaining a clean system.

6. An unexpected increase in volume/list size

The ISPs can suspect the companies purchasing the email list by the unexpected hike in their list size during a short period. Hence, they can put their IP address on the blacklist. Also, the companies delivering a larger volume of emails than others come under suspicion/ spam.

How to avoid getting on the blacklist?

As a marketer, you should avoid getting on the blacklist to make your email marketing campaigns successful. You must employ the best strategies to make your emails pass through the spam filters. You can adopt different ways as follows:

1. Spam tests

Always check the viability of your email campaigns through spam tests. Many tools and techniques are available that can check your domain name across a number of blacklists. This would help you to take remedial action in time.

2. Never purchase lists

There are high chances of you falling prey to the spam traps set up by the ISPs in case you choose to buy the email list. Moreover, they usually consist of old, stale, and illegitimate email addresses.

3. Filter your email list

Email hygiene is an essential factor here. Remove old, inactive, and bounced email addresses from time to time. Monitor the performance through data analytical tools. Pay close attention to the email open rate and click-through rates metrics and noticeable change, if any.

4. Segment your email list

Segmentation plays a vital role in identifying your target audience and understanding their needs and requirements. You should segment your email lists properly and further design the emails to suit the needs of the target audience.

5. Maintain consistency in your emails

Engagement, personalization, interaction, and consistency are crucial elements for audience retention in the long run. You must include the latest interactive content with a personalized touch in your emails to keep the users engaged. Stay consistent with the frequency of emails you send. Overall, add as much value as you can and provide them with what they're looking for!

6. Double opt-ins

It is a two-step verification process for confirming the subscription on the part of the recipients. You can reduce both fraud and spam complaints. The uninterested parties may also opt-out of the subscription, thereby maintaining a clean email list.

Related guide: What Is Double Opt-In and Why You Should Use It

Your email content should be free from spammy words. The image-only emails, poorly formatted HTML, ALL CAPS content, template copy, and "lorem ipsum" indicate spam mails as well. Keeping these points in mind is not enough. You have to monitor the campaign's performance continuously. But what if your IP address or domain name is already on the blacklist? Check it beforehand.

How to find out if you are on a blacklist?

These days numerous databases maintain track records of spam IP addresses and domain names. Popular blacklisting checker tools are:

What to do if you are on an email blacklist?

Usually, the ISPs maintain as small blacklists as possible to keep the emails flowing. So, there is nothing to worry about, even if your address appears on one of the blacklists. Around 15% of the email marketers said that their companies' email addresses had been blacklisted at least once in the last twelve months.

Well, most of the email service providers contact you and run you through the process of getting it fixed. They also reach out to the blacklisting services company to get your name removed from their lists. Alternatively, you can contact those companies. You have to follow the process, clean your mailing lists, and comply with the demands if any.

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Wrapping up

Blacklisting is a common issue with companies running email marketing campaigns. What matters is you learn the rules of this game to ensure none of your campaigns fail in the first place. Keeping the tactics in mind and designing the strategies wisely can reduce the probability of blacklisting.

Interactive content is the best way to nurture long-term customer relationships. It decreases spam complaints and increases email deliverability and click-through rate. What are you waiting for? Check it out now.

What you should do next

Hey there, thanks for reading till the end. Here are 3 ways we can help you grow your business:

  1. Talk to an email expert. Need someone to take your email marketing to the next level? Mailmodo’s experts are here for you. Schedule a 30-minute email consultation. Don’t worry, it’s on the house. Book a meet here.

  2. Send emails that bring higher conversions. Mailmodo is an ESP that helps you to create and send app-like interactive emails with forms, carts, calendars, games, and other widgets for higher conversions. Get started for free.

  3. Get smarter with our email resources. Explore all our knowledge base here and learn about email marketing, marketing strategies, best practices, growth hacks, case studies, templates, and more. Access guides here.

What should you do next?

Thanks for reading till the end. Here are 3 ways we can help you grow your business:


Get smarter with our email resources

Explore our email marketing guides, ebooks and other resources to master email marketing.


Do better email marketing with Mailmodo

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Talk to an email expert

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