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How to Stay Clear of Email Blacklists

If you’re wondering how emails get flagged as spam, look no further than the email blacklist. 

Ending up on an email blacklist means that you have a low-quality list and/or your content has been deemed untrustworthy, resulting in wasted time, lost sales and decreased ROI. Luckily, there are several strategies you can take to avoid ending up in this preventable situation. 

In this article, we’ll explain how to avoid being blacklisted, how to determine if your IP or email domain is on an email blacklist, why avoiding being blacklisted will save you time and money and how to get off of a blacklist if you find yourself on one. We’ll also detail the best practices to avoid email blacklists so that your emails have the best chance of generating increased traffic and engagement. 

Table of contents:

  • What is an email blacklist?
  • How to know if you’re on an email blacklist
  • Why avoiding email spam lists saves valuable time and money
  • How to get off of an email blacklist
  • Email best practices to avoid ending up on an email blacklist

What is an email blacklist?

An email blacklist is a database that tracks IP addresses and domains that are likely to send unwanted emails or spam. These spam blacklists work to ensure that illegitimate and harmful emails never get delivered. 

Email blacklists also have the unintended effect of occasionally preventing marketing campaigns from reaching their audience. This is because the standards for email deliverability are high—if an IP address or domain name acts suspiciously (ie. sending spam, scam emails, phishing, fraudulent emails, unwanted emails and emails from badly configured infrastructure), regardless of intent, blacklists will categorize them as spam messages. 

Although sometimes described as one entity, the email blacklist is a compilation of several blacklist databases that each set their own standards for email deliverability. There are many widely consulted public blacklists, including Composite Blocking List (CBL), XBL Exploits Blocklist and Spamhaus Block List (SBL). 

These three blacklists are all run by an international organization called The Spamhaus Project. Email service providers, such as Gmail, Outlook, and Yahoo, consult The Spamhaus Project to ensure that their users only receive legitimate emails in their inboxes. If you’re a Gmail user you may, for example, have seen a notification saying ‘This message seems dangerous’. Private companies can also create their own internal blacklists in an effort to block certain email addresses or domains from contacting them via email. 

These various blacklist databases function by collecting complaints against IP addresses or domains. These complaints can be manually recorded, such as when a user marks an email as spam, or automatically recorded based on factors such as bounce rate, spamtraps being recognized, engagement rate, or deliverability. 

Bounce rate refers to the percentage of emails that are returned to you, either because the email address does not exist, is no longer active, or the server of IP domain is blacklisted.

Engagement rate, often categorized as open rates and click rates, measures both the percentage of users engaging with your email and the quality of the engagement. Opening an email signals a basic level of engagement, whereas clicking on email links or replying to an email is a sign that the email provides value.

Deliverability, not to be confused with email delivery rate (more on this below), refers to the percentage of emails that arrive in inbox folders vs. spam, junk or promotion folders. You can use a tool like Hunter’s Email Verifier to check whether the emails you send to specific addresses on your list will bounce and ensure a higher deliverability.

While Spamhaus is perhaps the most well-known blacklist, blacklists like Barracuda, Senderscore and Spamcop also play a significant role in determining whether your email campaigns get delivered.

How to know if you are on a blacklist 

If your bounce rate is high, it could mean that your IP address or domain has been blacklisted. 

Deliverability is often confused with the delivery rate, which measures how many of your emails did not bounce. An email bounces if it is sent to an inactive or nonexistent email, like when you make a typo in the intended email address and it comes back to your inbox. With delivery rate, emails are counted as delivered even if they land in the spam folder. As such, the delivery rate by itself does not tell the full story.

One reason marketers might lean on the delivery rate is that it’s easier to measure than deliverability. While email services will provide your delivery rate they will not quantify your deliverability. There are apps that claim to measure deliverability, but this number is often approximated by using the open rates provided by email services. 

If your open rate is high, this likely indicates that your emails are going to the intended folder as users are more likely to open an email in their inbox than in their spam. If your bounce rate is high, it could indicate that your email is on a blacklist or a number of blacklists.

Although, at first, being on an email blacklist will see your emails sent to the spam folder, if you don’t take action, mail services will stop accepting your emails entirely, until your reputation is improved.

If you’re asking yourself, “is my email blacklisted?”, you should immediately run an email blacklist check by looking at public blacklists for your IP address or domain. You can check this directly on blacklist websites, but you can save time by using an online remote block list or real-time blackhole list (RBL) tool like MXtoolbox to check several blacklists at once. 

If you think you are in fact on a blacklist, it can be tricky to determine which specific blacklist you are on. Tools like Senderscore, BarracudaCentral and Reputation Authority will give you a score that ranks your email reputation, although they will not necessarily tell you if you are on a blacklist. Similarly, running a test on Glockapps can give you an idea of whether you need to invest time investigating whether your IP address or domain is on a blacklist.

After you’ve completed email blacklist testing, if you are in fact on a blacklist and can determine how many emails are ending up in spam, then you can calculate true deliverability manually. To do this, simply divide the number of emails that got delivered (excluding spam emails) by the total number of emails sent. Then, multiply that number by 100 to get a percentage.

For example, if you sent 100 emails, 50 got delivered and 50 went into the spam folder, you would get the following deliverability rate:

(Delivered Emails / Total Sent) x 100

(50 / 100 ) x 100 =  50%

To avoid ending up on an email blacklist, make sure you’ve kept your contacts list clean and periodically check your email reputation and run email address blacklist checks. Keeping tabs on your reputation is a good habit and these tools mentioned above can help you identify problems before they arise. 

Why avoiding email spam lists saves valuable time and money 

Email marketing has an incredibly high ROI—for every $1 you spend, you’ll get an average of $42 back. Email marketing is also one of the most consistent and stable marketing channels because it is not subject to ever-changing algorithms that affect your visibility and reach (like we see on social media platforms and search engines like Google).

The effectiveness of your email marketing campaigns, therefore, depends solely on two factors: your strategic email marketing efforts (i.e. your ability to deliver captivating email content that will boost engagement) and the ability to stay off email blacklists. In light of this, protecting the deliverability of your email list should be a high-priority task. 

In more detail, avoiding email block lists saves you time and money in regards to:

  • Your marketing budget. No matter how well-crafted your email, it cannot be effective if it does not land in front of clients. Marketing dollars are wasted when your team spends time creating emails that are never read. Ensuring that your emails are properly delivered is the preliminary step to successful email marketing. 
  • Efforts put into getting off of email blacklists. Once you are on a blacklist, it can take considerable effort to get your IP address or domain name back in good standing. Some businesses choose to pay for services rather than spending their own time on this process, as each blacklist requires a unique removal procedure. 
  • Avoiding legal issues. As data and privacy laws evolve, regulations surrounding spam filters are becoming more heavily defined and enforced. Even an unintentional breach of consent can translate into hefty consequences under laws such as the GDPR

How to get off an email blacklist 

The first step of email blacklist removal is to find out exactly why you were blacklisted in the first place. There are three categories of issues that may apply to your situation: technical, policy and evidence-based.

  • Technical: If the configuration of your email system is not up to standard, it raises a red flag for blacklists. Common technical reasons that may lead to being blacklisted include faulty DNS records and SMTP banners, as well as email lists with a high bounce rate. 
  • Policy: Each blacklist has its own policies and some may block IP addresses from specific countries or internet service providers. Because this is based on fixed qualities rather than behavior, it may be difficult to get off these lists if you do not fit their specific requirements. 
  • Evidence-based: Blacklists are constantly monitoring complaints. If algorithms detect suspicious behavior, such as sending a number of emails to inactive or non-existing email addresses or to lists with high bounce rates, then a complaint is filed against your IP address or email server, which may land you on an email server blacklist or an email domain blacklist. Being hacked via malware can unfortunately result in blacklisting if hackers gain access to and then use your IP address to send unsolicited emails. Your domain or IP could also be identified as suspicious if a significant portion of customers mark your content as spam. Recipients will then see a warning notification telling them not to open your email.

Communicating with blacklists

Once you know why you were blacklisted, there are several ways to go about delisting. You may have to try more than one way, as each blacklist has its own protocols for removal. Most blacklists lay out their specific removal process on their website.

Here are the most common processes for removing yourself from an email blacklist:

  • Self-Service removal. While it is not common, some blacklists will allow you to remove yourself from their list by manually entering their site and searching for your IP address or domain name. Be sure to understand what caused you to be put on the blacklist and resolve any issues first, otherwise you risk being relisted. 
  • Time-based removal. Many blacklists will automatically remove you in 1-2 weeks if you show that you are following email best practices. Repeat offenders stay on these lists for longer, so it is important to keep your systems up-to-date and fix issues as soon as possible. 
  • Contact the blacklist. If you are following email best practices and have not been automatically removed after a few weeks, then contacting the blacklist operator may speed up the process. Make sure to resolve all technical issues before contacting them so they can help you. 
  • Permission pass campaigns. Email policies are ultimately a matter of permission and whether your recipients consented to receive communications in the first place. Unfortunately, subscribers often neglect to opt-out of emails when they are no longer interested in them. As such, your email list can quickly become outdated. In order to revamp your list and ensure that you are only sending solicited emails, you can run a permission pass campaign. 

At Mailigen, we require all our users to follow best practices in order to stay off blacklists. If we notice that a user is on a blacklist, we will look into why and notify the user. If the user doesn’t then follow best practices, their account will usually be suspended until they do.

Permission pass campaigns work by creating a targeted campaign that sends emails only to subscribers who consistently do not open your emails. In this campaign, you will ask whether the subscriber wishes to stay on the email list or unsubscribe. Anyone who replies negatively or does not open the email should be removed from your email list. 

Although it may feel counterproductive to delete large portions of your email list, running a permission pass campaign actually allows you to reach more customers by helping you get off and stay off blacklists. Sending emails directly to the inbox of a smaller email list is more effective than landing in the spam box of a big list. The increase in open rate that results from a permission pass campaign provides compelling evidence that your IP address or domain is not spam. 

Email best practices to avoid ending up on an email blacklist

Landing on an email blacklist is both preventable and treatable by following email best practices for email marketing. 

Use clear opt-ins 

Lead magnets are a valid marketing technique used to collect emails. By offering valuable guides or promotions in exchange for an email, you can grow a list of ideal customers. However, if someone feels tricked into subscribing to your email list, they are more likely to file a complaint against you. 

The purpose of collecting emails should be clear to the user. Before they type their email address, they should understand what their email will be used for and what type of content they will receive. 

Automate your processes 

Manual entry increases the chance of making a typo or another human error when adding email addresses into your subscriber list. If you input the wrong email address, one of two things can happen: the email will bounce back and decrease your email delivery rate, or the email will be sent to the incorrect person, which may lead them to mark your email as spam. 

Avoid spamtraps

Spamtraps are fake emails created by internet service providers and blacklists to catch spammers. If you scrape data or buy email lists (which we wouldn’t recommend anyway), it’s possible that there are spamtraps hidden within them. There are two types of spamtraps: pristine and recycled. Pristine spamtraps are completely fabricated and have never belonged to a human being. Because the email does not belong to anyone, it cannot be used for opt-ins and therefore any campaigns sent to these emails are unsolicited. 

On the other hand, recycled spamtraps may have belonged to someone years ago, but have become inactive. It’s possible that a recycled account opted in to an email list while it was still running, but has since been repurposed as a spam trap. 

There is no way to differentiate between a spam trap and an inactive user. That is part of the reason why regularly cleaning your email list is important. 

Clean your email list regularly

Cleaning your email list refers to deleting inactive users. Users who have not opened emails in several months are likely not interested in receiving future emails and they might even be spamtraps. If you are hesitant to delete users without contacting them, you can send a permission pass campaign with a targeted offer to try and revive their interest. However, if the permission pass campaign does not work, it is best to delete inactive users—especially as some spamtrap emails will open emails automatically. 

How often you check your list hygiene depends on the frequency of your campaigns. If you email your list less than once every quarter, then it’s enough to simply clean it before each campaign. However, if you send emails on a weekly or monthly basis, you should clean your list periodically every six to eight weeks. 

“It’s best is to stay with above an 18-20% average open rate. If it goes below, clean your list or send re-confirmation emails to inactive addresses and then remove them from your list,” recommends Aleksandrs Vilums, Mailigen’s head of email delivery operations.

It’s also favorable to clean out your list after getting a large influx of new subscribers. By prioritizing clients that frequently open your email, you lower your chances of being put on blacklists and also create a curated, engaged audience that has no interest in unsubscribing. 

Final thoughts

Ending up on an email blacklist can hurt your email deliverability rate, which will cost you valuable time and money and could negatively impact your customer relationships. 

The good news is, landing on an email blacklist is entirely preventable and avoidable. Whether you are trying to remove yourself from a blacklist or avoid them, implementing email best practices is the foundational step to creating successful campaigns. 

If you do end up becoming blacklisted, follow the steps laid out in this article to get off of an email blacklist and back on course with your email marketing campaigns.

How to Stay Clear of Email Blacklists
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