Email blacklist: What it is and how to check (2026)

Landing on an email blacklist feels like your ecommerce business just went invisible overnight. For example, your email open rate hovers around the 30% industry standard, then suddenly plummets to a measly 4%.

If this sounds familiar, you might be dealing with an email blacklist. It quietly blocks your messages before they ever reach your customers’ inboxes. Abandoned cart recovery emails stop converting, customer retention drops, and revenue takes a hit.

To avoid this, you should run an email blacklist check. This allows you to make adjustments to protect future campaigns. 

In this guide, you’ll learn what an email blacklist is and how to check your status using free tools. You’ll also discover how to clear your domain or IP address and prevent it from happening again.

What is an email blacklist and why is it harmful?

Let’s start with a simple answer. An email blacklist is simply a record that contains IP addresses or domains flagged by spam filters. Servers then use these lists to identify addresses to block.

The entire point of an email blacklist is to protect users from unwanted messages sent from untrustworthy sources. A Kaspersky report shows that 44.99% of all emails sent worldwide in 2025 were classified as spam. What’s more, 24% of users never check their spam folders. 

Sometimes messages sent from the address in question are directed to a spam folder. Other times, they’re blocked completely. 

When your domain or IP ends up on an email blacklist, it becomes difficult to reach your subscribers. 

For ecommerce businesses, the impact is more significant. Your abandoned cart emails, product updates, and promotional offers never land in your customers’ inboxes. 

This directly affects your revenue, weakens customer relationships, and reduces retention. In fact, a Kickbox report shows only 11% of companies state that they don’t experience these issues. 

Additionally, modern blacklisting isn’t just about sending too many emails. Email providers now check things like:

• Proper authentication setup (SPF, DKIM, DMARC)
• How people interact with your emails (opens, clicks, unsubscribes)
• Complaint rates and spam reports

The good news is that email platforms like Omnisend now include deliverability monitoring features. These tools help you spot and fix problems before your messages land on an email blacklist.

How to check if your email is blacklisted (email blacklist check)

If you’re asking, “Is my email blacklisted?”, you’re not alone. Many senders only notice a problem when deliverability, open, and engagement rates drop.

To know your status, run a quick email blacklist check. Take note of these three main types of email blacklists:

1. Enterprise spam firewalls are normally used by corporate IT departments. Examples include McAfee and Barracuda.

2. Private blacklists are maintained and circulated by ISPs. Gmail, for example, has its own internal blacklists it uses to monitor and filter emails.

3. Public blacklists are open for anyone to check, at no cost. They’re your best starting point for a blacklist email check.

Step-by-step guide: Using MX Toolbox to check your blacklist status 

This is one of the easiest ways to run an email blacklist check. MXToolbox checks your IP address against more than 100 publicly available blacklists.

Here’s how to check email blacklists using this tool:

1. Open the MXToolbox email blacklist checker

2. Enter your domain name (like yourstore.com) or sending IP address

3. Click the Blacklist Check button

4. Read your results

If you see OK next to a green checkmark, it means you’re not blacklisted. 

However, if you see LISTED alongside a red mark, your IP or domain appears on a blacklist. Click the Details button to see the exact reason.

Other top email blacklist tools you can use include:

• DNS Stuff: Great for deeper DNS and blacklist insights
• Spamhaus: One of the most reliable blacklist databases
• DNSBL: A simple tool for quick IP lookups
• MultiRBL.Valli.org: Checks your IP across 200+ blacklist servers

These free tools help you check your email blacklist status quickly. However, they can’t prevent you from landing in one. To receive alerts before you’re added to a blacklist, use Omnisend’s built-in email deliverability monitoring.

Checking IP address vs. domain vs. email address blacklists

When running an email blacklist check, you should know exactly what’s being blocked. 

1. IP address check 

This checks the server that sends your emails.

To find your IP:

• Open one of your sent emails and click the three dots next to Reply
• Select Show original

• View the full email headers — the IP address will show next to the SPF

• Copy that IP and run it through a blacklist checker

2. Domain check

This checks your website domain, such as yourbrand.com. Here’s how to check if your domain is on an email blacklist: 

• Copy your domain URL
• Paste it into a tool like MXToolbox

3. Email address check

While less common, some tools let you check specific sender addresses. 

How often should you monitor your blacklist status?

Don’t wait until your marketing campaigns fail before you start wondering: Is my email on a blacklist? Run regular checks to spot and fix issues before they get more serious.

Here’s a cadence you can follow:

• High-volume senders (daily/weekly emails): Check weekly
• Moderate senders: Check monthly
• After every major campaign: Run a quick check to ensure deliverability

How do you get blacklisted?

The answer is simple: ISPs reserve the right to blacklist any IP address they want, for whatever reason. They are not obliged to hear your deliverability concerns or clean up your non-compliance issues.

There are, however, common things that can harm you as a sender and tag you as a blacklisted email sender:

• Poor email list hygiene: Failing to regularly clean your list hurts your sender reputation, increasing your risk of getting blacklisted. You could be sending emails to invalid or inactive contacts and neglecting to honor unsubscribe requests. Many ISPs also use spam traps, which are addresses that appear real but aren’t. Sending emails to these accounts reflects poorly on your list management practices.
• Hackers: Hackers can access your account and send spam messages. They could also be spoofing your email address, meaning they’re piggybacking off your IP address to send fraudulent emails. A sign of spoofing is receiving a lot of error messages for order confirmations, shipping updates, or other ecommerce emails you didn’t send.
• High volume of emails: Spammers send the most emails in the world. So, if your IP address has a higher email delivery volume than others, this can signal spammy behavior. If you blast your entire list with offers every day, this could trigger spam filters over time. Your IP address may land on an email blacklist even if your content is legit.
• Increased email volume: Another spam indicator is a sudden spike in emails sent from an IP address. If you suddenly go from sending 500 emails a week to 50,000 without warming up your list, you can trigger email blacklist filters. This often happens to ecommerce stores during Black Friday or big holiday sales. Grow your email volumes organically to dodge blacklist and spam filters.

• Spam complaints: Every ecommerce business receives complaints about its email marketing from time to time. That’s not necessarily a bad thing. However, complaints that exceed the required 0.3% threshold can be a big problem, leading to bounced emails or ending up in the junk folder. This can happen when you send irrelevant offers or too many emails.
• Bad email content: Several ISPs filter emails by keywords found in your email’s copy. Words like “money-back guarantee,” text written in all caps, colored fonts, and many exclamation marks (!!!!) are red flag content that can put you in an email blacklist. This also increases the likelihood that subscribers will mark your emails as spam. Keep your copy clean to avoid these issues. 

Omnisend automatically verifies your list and removes risky addresses before you send any emails. This helps you stay off any email blacklist and keep your ecommerce marketing campaigns flowing smoothly.

What happens when you’re on an email blacklist

Being on an email blacklist can result in a chain of problems. Sender reputation drops, emails stop reaching inboxes, campaigns lose impact, and revenue takes a hit.

Imagine that you have no clue that your IP address was flagged as a blacklist email. So, you go about your regular email marketing activities and launch a campaign. We’ll say it’s a sales promotion and John is on the contact list. The email goes to his internet service provider (ISP), which checks your IP address against whatever email blacklists his ISP uses. 

Bingo, there’s a match. Your email is discarded. John either never gets news of your sales promotion or, if he does, it’s delivered to the spam folder that he rarely checks. 

This blockage clearly has a harmful effect on email deliverability. Being identified as a blacklisted email sender can wreak havoc on your email marketing efforts.

Here’s what to expect:

• Reduced email deliverability: Landing on a major email blacklist can lower your deliverability by 90% in hours. It means almost every abandoned cart recovery, customer retention, and promo emails will never reach subscribers.
• Damaged sender reputation and trust: About 10% of consumers say they lose trust in a brand if its emails consistently land in their spam folder. Email providers also trust you less, and future campaigns are more likely to be filtered.

• Revenue loss: For every million emails sent, deliverability issues can cost ecommerce brands over $15,000 in revenue. This includes missed abandoned cart recoveries, retargeting emails, and failed promotional campaigns.

But really, how worried should you be?  According to Omnisend Deliverability Manager Serhii Chernenko, it depends on what blacklist you’re on.

And it’s absolutely essential that you regularly keep an eye on your email campaign stats, such as click rates. Persistently check the domain opens for any sharp drop-offs as well. 

If you get blacklisted, don’t expect a quick solution. While some IP blocks can be cleared in 24 to 48 hours after fixing the root cause, it takes longer to restore your reputation. A damaged domain reputation can take up to six to 12 weeks to fully recover.

Omnisend tracks your deliverability metrics and alerts you before you end up on an email blacklist. 

The nuts and bolts of an email blacklist

Every email you send carries a unique string of numbers called an IP address. Think of it like a return address on a physically mailed letter. It tells receiving servers where your email came from.

You can trace the location of the email sender by referencing the IP address.

When your email reaches an inbox provider, it checks the IP address against an email blacklist. Officially, blacklists are known as Real-time Blackhole Lists (RBL) or Domain Name System Blacklists (DNSBLs or DNS blacklists). They store lists of IP addresses and domains that have shown risky sending behavior.

Email providers also verify your identity using SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication). These security checks prove that you’re a trusted sender. However, if they’re missing or set up incorrectly, email blacklists are much more likely to flag you.

Omnisend automatically handles technical setup like SPF, DKIM, and DMARC, so you don’t have to.

How to remove email from blacklist 

If you find your IP address or domain on an email blacklist, don’t panic. Every major blacklisting company provides a way to appeal your status and have your email delisted. The exact removal procedures vary by provider, but most follow a similar approach.

Step-by-step delisting request process

Here’s how to get off email blacklists and get your ecommerce campaigns back on track:

• Identify where you’re listed: Run an email blacklist check using tools like MXToolbox or Spamhaus to see exactly which list flagged you
• Fix the root cause: Learn why you got flagged (spam complaints, poor list hygiene, or suspicious activity) and solve the issue
• Locate the removal form: Visit the blacklist’s website and find the delisting or removal request form

• Submit your request: Fill out the required details, such as your IP or domain, and what you’ve done to fix the issue — keep your message short and professional
• Confirm and verify: Check your email for a confirmation link, click on it, and the blacklist provider will review your case

Expected timelines for blacklist removal

Delisting doesn’t always happen instantly. It depends on the type of email blacklist that flags your IP or domain. 

Here are the average timelines:

• Automatic removal lists: 24 to 48 hours
• Stricter lists (like UCEProtect Level 1): One to two weeks

In many cases, first-time email unblacklist requests succeed if you show clear fixes. However, if the issue persists, removal may take longer.

What to do while waiting for removal

As you wait for delisting, use that time to strengthen your email setup and reputation to avoid email blacklists.

Here’s what to do:

• Pause or limit sending: Stop sending campaigns until you’re cleared, or only send to your most engaged subscribers
• Fix your email practices: Clean your list, improve content quality, secure your account from hackers, and set up authentication
• Document your fixes: Keep a record of the changes you made, as some email blacklist providers may ask for proof
• Get help from your ESP if needed: Reach out to your provider’s support team for guidance on delisting

If your current provider isn’t helping, you can switch to a more reputable platform. Omnisend has strong relationships with blacklist providers and can help you expedite the removal process. It also provides sender reputation warming strategies to help you re-enter the inbox safely.

How to avoid a blacklist

Who wants to deal with petitioning for removal from an email blacklist? Our best advice is to be proactive, so you never have to deal with an email spam list. Adhere to the following best practices to stay on the right track. 

Collect emails judiciously

Email lists that contain bad addresses are the predominant culprit for getting sent to an email blacklist.

Worst case, some addresses are spam traps. As mentioned before, they appear real but don’t belong to a real person. Their only purpose is to identify spammers and senders not utilizing proper list hygiene and to add them to email blacklists. 

Instead, grow your list organically. Collect emails with popups and landing pages on your ecommerce website. Omnisend’s intuitive form builder provides email validation features that help you collect verified addresses from the start. 

Use double opt-in for email subscribers

A double opt-in is a two-step email verification process. Step one—the user signs up for the mailing list on the website. In the next step, an email is sent to the user with a link to confirm their email subscription.

Double opt-in practices are good for avoiding email fraud, as they ensure that email subscribers are real people genuinely interested in receiving your marketing emails.

By enabling them, you also avoid spam complaints (and the email spam list), since customers won’t discover they are on a mailing list they did not request to join. Double opt-ins are an email marketing best practice and one of the surest ways to avoid the junk folder.

Omnisend offers a built-in double opt-in capability that automatically handles the email confirmation process for you. 

Keep a clean email list

Collecting emails the right way is one thing. But it doesn’t take care of accumulated bad addresses. So, make list hygiene part of your routine, at least once quarterly.

• Remove bounced email addresses. Make sure to distinguish the hard bounces from the soft bounces to avoid discarding addresses experiencing a temporary hiccup.
• If a subscriber hasn’t opened an email in six months, run a re-engagement campaign. Then, remove them if they remain inactive. 
• Track metrics like spam complaints, bounce, open, click, and engagement rates. Remove old addresses exhibiting weak engagement.
• Make it easy to unsubscribe. If a client requests removal from your email subscriber list, honor that promptly.
• Segment your list by engagement (active vs. inactive users). This helps you identify dormant addresses to remove. 

Omnisend automatically segments your audience, flags invalid addresses, and tracks key metrics, so your list stays healthy without manual work.

Protect your server

It’s crucial to check that your server is clean of any malware or bots. These harmful programs hijack your email domain or IP address to send bogus emails, so you can end up on an email blacklist even if you’ve done nothing wrong.

To enhance security, follow these steps:

• Run regular malware scans and use intrusion detection software. Tools like BitNinja and Imunify360 work well.
• Properly set up SPF, DKIM, and DMARC authentication. These prove that your emails are legitimate and protect your domain from spoofing.
• Use strong passwords and two-factor authentication. They prevent unauthorized hackers from accessing your server.
• Run regular security checks on your system. These help you identify unusual sending activity and login locations.

Platforms like Omnisend help reduce server security risks without technical complexities. It handles security monitoring, authentication, and protection on your behalf. 

Conclusion

Unfortunately, nearly every ecommerce brand will end up on an email blacklist at some point. However, the situation isn’t permanent and doesn’t have to stop your progress. 

You’ve seen what blacklists are, how to check your status, fix issues, and even get delisted. More importantly, you know how to avoid being blacklisted in the first place. 

Your email deliverability depends on trust. When you protect your sender reputation, emails reach the inbox more often. The key is proactively monitoring your metrics, cleaning your email list, and fixing problems early. Also, don’t forget to warm up your email domain when you restart campaigns.

If you’ve run into problems with your ESP and you’re ready for a clean slate, start Omnisend for free. It provides deliverability and list management tools to help you avoid ending up on email blacklists. Plus, you can enjoy its award-winning 24/7 support.

FAQs