An email blacklist is a list of IP addresses, emails, and domain names that have been identified as senders of spam messages. Internet service providers, email service providers, and organizations use blacklists to minimize the number of unsolicited emails sent to users.
Email blacklists are also called Domain Name System Blacklists (DNSBLs) or Real-Time Blackhole Lists (RBLs). Some of the well-known blacklists include Spam and Open Relay Blocking System (SORBS), Spamhaus Block List (SBL), and Barracuda, to name a few.
These lists, maintained by independent organizations, are available to the public.
There are two types of blacklists:
If the domain or IP address is blacklisted, mailings will go through spam filters or not be delivered at all. You can find spam email examples online to be familiar with what these messages look like.
Some of the most common reasons why your domain or IP address could be listed in blacklists are spam complaints and spam traps.
If your emails are not getting through, spam complaints could be the reason why. This happens when someone reports your email as spam, or when you send emails to people who didn’t consciously opt in to receive it. It can also happen when you send an email to a list that you haven’t engaged with in a while.
As a result, your email is marked as spam by the recipient’s email provider, which can lead to your messages being blocked or sent to the spam folder.
Spam traps are email addresses created for the sole purpose of catching spammers who send unsolicited emails.
When a spammer collects email addresses using automated means, they will inevitably collect some spam traps along with genuine addresses.
If you have a spam trap or a kind of email honeypot address in your email list, it can hurt your reputation as a sender and get your IP address or domain blacklisted.
If you’re experiencing any of the below, it may mean that your domain or IP address has been added to an email blacklist:
If you’re unsure whether you’ve been included in a blacklist, there are available tools that can confirm the blacklisting of a domain or IP address. Here are the steps that you should take to get your domain or IP address removed from there.
The first step is to identify which blacklist you are on. To verify the domains and IP addresses of the sending server, email services refer to authoritative blacklists such as Spamhaus, SpamCop, and SORBS.
There are special checkers that you can use to see if an IP address or domain is on a blacklist. Some popular blacklist checkers include MxToolbox, DNSBL.info, DNS Checker, Sitechecker, Site24x7, and BlacklistMaster. To use these tools, simply enter your IP address or domain name into the search field and click “Blacklist Check”.
Analyze your domain/IP status. A green checkmark means that your server is not detected in the list:
Send an email to the support team of the site whose blacklist you are on. Explain in detail what happened and what actions have been taken to resolve the problem. Once the problem has been fixed, you will be taken off the list automatically.
Getting blacklisted can harm your email reputation and the business as a whole. Here are some tips to help you avoid it:
One of the most common reasons why businesses get blacklisted is because they purchase or rent recipient lists. This is a huge no-no in email marketing, as it almost always guarantees that you will end up on a blacklist.
When you purchase or rent a list, you have no idea who those email addresses belong to or whether the owners of these emails would actually want to receive your emails. This often leads to a high number of spam complaints, which is something that blacklist providers take very seriously. So it’s better to build an email list on your own organically. It’s slower but much safer that way.
Some of the most common list-building techniques include lead magnets and exit-intent pop-ups.
A lead magnet can be a compelling offer that your website visitors cannot resist. It can be an exclusive discount, a giveaway, a free limited subscription, or a piece of content. In exchange for your offer, your audience can give you their email address.
Exit-intent pop-ups, on the other hand, can help you capture the email address of users who are already leaving your website. Right before they do, your pop-up can make them stay for a little longer. When designed well, your exit-intent pop-up can pique your visitors’ curiosity and make them reconsider your offer.
If you’re not monitoring how recipients interact with your emails, you could be unintentionally harming your sender domain reputation. When your emails are not being opened, it signals to email service providers that your subscribers don’t find your emails interesting or relevant. They may eventually mark you off as a spammer, which can lead to your emails straight to the spam folder.
Make sure to track key metrics like open rate and click-through rate, as well as unsubscribes and email bounces. This data will give you a good idea of how engaged your subscribers are, and whether or not they’re actually interested in the content you’re sending.
Duolingo sends out unobtrusive re-engagement emails to ask if their subscribers plan to take lessons and remind themselves once again.
Using single opt-in can be faster when you want to collect email addresses, but it can be risky. When you don’t require a confirmation or an additional step before an email is added to your list, you might end up with fake emails or mistyped email addresses, which can cause your future emails to bounce. This will hurt your deliverability and harm your reputation.
When you apply an active opt-in process (also called double opt-in), people have to take an extra step to confirm their subscription before they’re added to your list. With double opt-in, you can be sure only those who really want to be on your list are on it. In turn, this will reduce the chances of getting complaints or having your emails marked as spam.
This is how a verification email looks like:
Keep an eye on the email list hygiene. Subscribers may lose interest in your newsletters – this is normal. If you see that some members of your audience do not engage with your emails or not open them at all, conduct a campaign to re-engage them.
Never forget to include an unsubscribe URL in your marketing emails so that people can opt out of your list if they want to.
Those users who continue not to open your newsletters should be removed from your list. Otherwise, they may eventually have a bad effect on your email deliverability. When a significant fraction of your audience continually skip your emails or delete them right away, email service providers might think that your emails are irrelevant, and they could decide to block your emails in the future.
When it comes to blocking issues, the most important features of your emails are links. Linking to pages outside your domain or using a link shortener (practices commonly done by spammers) can be a red flag to security providers, which could lead to blacklisting.
An email blacklist is a list of domains and IP addresses that are considered to be spam. Email providers use blacklists to protect their users from spam. When an email from a blacklisted address or domain is received, it is typically blocked or sent to the recipient’s spam folder.
Email blacklists are maintained by both public and private organizations. Email providers may also maintain their own internal blacklists.
Email services may blacklist emails from certain IP addresses for a number of reasons. If you suspect that your domain or IP address may have been blacklisted, use free tools like MxToolbox to check your email against known blacklists. Then contact the site’s support team to explain what occurred that landed you on the blacklist and how you fixed the issue.
