A Complete Guide on Email Blacklist in 2025

Your cold emails are landing in spam, even when you follow the proper process.

Bounce rate goes up, open rates go down, and you stop getting email replies.

In most cases, the issue isn’t your content or targeting. But, there is a high chance that your domain or IP has been blacklisted.

What happens when you’re blacklisted?

• Your emails stop reaching inboxes
• Your sender reputation gets damaged
• ESPs throttle or block your future emails
• Campaigns fail even with strong messaging

Personally, I’d say one small mistake can get you blacklisted and hurt your deliverability before you even realize it.

In this blog, let’s learn about the meaning of email blacklist, how it works, and tips to avoid it, and how to remove yourself from blacklisting. Let’s get started.

What is Email Blacklist?

An email blacklist is a set of domains and IP addresses known for sending spam, malicious, or unwanted emails.

These lists are managed by popular email service providers like Gmail and Outlook. They are also maintained by anti-spam organizations, security services, and internet service providers.

These organizations maintain these blacklists to protect users from phishing, malware, and unsolicited messages.

There’s another popular term coined for email blacklist – Real-time Blackhole Lists (RBLs) or DNS-based Blackhole Lists (DNSBLs).

Next, let’s understand the types of these blacklists.

Types of Email Blacklists

Here are the quick four types of email blacklists explained. 

1. IP-Based Blacklists
2. Domain-Based Blacklists
3. Public Blacklists
4. Private Blacklists

1. IP-Based Blacklists

An IP-based blacklist refers to a database of IP addresses that are involved in sending spam or malicious emails. ISPs maintain these lists of IP addresses to block emails originating from those IP addresses that have been flagged as malicious. It allows these regulations to prevent spam from reaching users’ inboxes.

2. Domain-Based Blacklists

A domain blacklist refers to a list or database of domains that are known to be active in spam, malicious activity, or poor email practices. If your domain gets blocked, your sender reputation decreases and remains the same, even if you switch to a different service or change your IP addresses.

3. Public Blacklists

A public blacklist is an open database that has a list of IP addresses or domains identified as sources of spam or suspicious email activity. These lists of IP addresses and domains are maintained by anti-spam organizations, such as Spamhaus, SpamCop, and Barracuda, to enable senders to check their sender status and submit removal requests if necessary.

4. Private Blacklists

A private blacklist is an internal list of IPs and domains maintained by email providers or organizations to block unwanted or suspicious traffic. Unlike public blacklists, these are not publicly accessible, and you won’t know if you’re on them. Each organization uses its own criteria to manage the list.

Pro Tip: When checking whether your domain is on a blacklist, start with public blacklists. They’re easier to check and fix, plus most people primarily get blacklisted on public blacklists. 

With the types of email blacklists covered, let’s move on to how blacklists work.

How Does Email Blacklist Work?

Let’s learn how email blacklisting works, from start to finish. 

1. Email Activity is Monitored
2. Suspicious Behavior is Detected
3. IP or Domain Gets Blacklisted
4. Mailbox Providers Check the Blacklist
5. Emails Get Blocked or Sent to Spam
6. Your Email Deliverability Suffers

1. Email Activity is Monitored

Every single time you send an email, the email service providers monitor your behaviour. Every action, such as how many emails you send, how often you send them, how many bounce back, and how recipients react, is monitored. There is a possibility that even the slightest mistake can raise a red flag.

2. Suspicious Behavior is Detected

If your emails keep hitting the spam traps or your recipients mark them as spam, it damages your sender reputation. The email service providers may start seeing you as a risky sender and flag you if this happens often. As a result, it becomes hard to reach people who are genuinely interested in receiving your emails.

3. IP or Domain Gets Blacklisted

If your sender reputation drops, there are high chances that your IP or domain can end up in a blacklist. This happens when your bounce rate is more than 0.3% and spam rate is more than 0.1%. Even genuine senders end up here without realising that they crossed a line.

4. Mailbox Providers Check the Blacklist

The receiving server checks whether or not your address is on any blacklist, when you send an email. This plays an important role and decides if your email ends up in the spam or the inbox.

5. Emails Get Blocked or Sent to Spam

If you’re on a blacklist, your emails might never make it to the inbox. Either they get blocked completely, or they’re pushed straight into the spam folder, and your recipient will never see them.

6. Your Email Deliverability Suffers

Once you face email deliverability issues, your emails stop reaching the inbox. As a result, your open rates drop, engagement goes down, and your important messages get ignored.

Now you must have figured out how email blacklist works, let me help you know the reasons your email gets blacklisted.

Why Do You Get Blacklisted?

Here are the main points that I’ve identified to help you know why your email or domain gets blacklisted.

• High spam complaints (over 0.1%) damage your sender reputation and can get you blacklisted.
• A poor-quality email list leads to high bounce rates and lowers trust with email providers.
• Spam traps flag your domain or IP as spam.
• A sudden increase in email volume can trigger filters.
• Too many images or promotional content can block your emails from reaching inboxes.

Now that you know why emails land in spam, here’s how to check if your domain is blacklisted.

How to Check if Your Email or Domain is Blacklisted

I follow this step-by-step process of getting your domain delisted. 

1. Use Online Blacklist Check Tools
2. Look for Email Deliverability Issues
3. Monitor Bounce Rates and Spam Complaints
4. Check with Your Email Service Provider

1. Use Online Blacklist Check Tools

If you think your domain is blacklisted, the quick way to check it is to use online blacklist check tools. I rely on tools like MXToolbox, MultiRBL, and Spamhaus because these tools are free, simple to use, and can quickly alert you to any issues that could affect your email delivery.

2. Look for Email Deliverability Issues

If your emails are missing inboxes, there’s a strong chance your domain or IP has been blacklisted. Monitor key metrics like open rates below 15%, deliverability under 95%, and delays in message delivery as these are signs of a blacklist issue.

3. Monitor Bounce Rates and Spam Complaints

Monitoring bounce rates and spam complaints is an important part of the process in your email analytics. 

If you’re seeing:

• Hard bounce rates above 0.3%
• Spam complaint rates over 0.1%
• Soft bounces are going up regularly

It’s time to take a closer look. These are strong indicators that something’s off, and blacklisting could be one of the reasons.

4. Check with Your Email Service Provider

Most email platforms (like Gmail, Outlook, or Mailchimp) offer reports on your email performance.

You can reach out to their support team and ask for details like:

• Bounce tracking
• Authentication status (SPF, DKIM, DMARC)
• Blacklist alerts or warnings

They’ll tell you if your domain or IP is flagged anywhere.

My recommendations: I make it a habit to check these metrics every Monday morning. Those few minutes of checking can save you weeks of headaches later.

How to Get Your Email/Domain Removed from a Blacklist

You must be wondering if it is even possible to get your email removed from a blacklist. Well, it certainly is. Here is how.

1. Check on Which Blacklist You’re Listed
2. Find the Reason for Blacklisting
3. Fix the Issue of Your Email Blacklisting
4. Request Delisting
5. Monitor and Follow Up

1. Check on Which Blacklist You Are Listed

To find out if your domain or IP is blacklisted, use trusted tools that show where you’re listed and why. Here are some helpful tools to use:

• MXToolbox
• MultiRBL
• Spamhaus
• Blacklist Check (WhatIsMyIP)
• Sender Score

These platforms can also provide details about what triggered the listing and what steps to take next.

2. Find the Reason for Blacklisting

Visit each blacklist’s website to understand exactly why you were listed. Common reasons include spam complaints, hitting spam traps, authentication failures, or compromised accounts.

3. Fix the Issue of Your Email Blacklisting

Do not request removal without addressing the underlying issues. First, clean up your email list by removing invalid and inactive addresses. Next, set up proper authentication (SPF, DKIM, and DMARC), secure any compromised accounts, and avoid using spammy language.

4. Request Delisting

Each blacklist has its own delisting process. While Spamhaus requires using their removal portal with detailed explanations, SpamCop has mostly time-based automatic removal. On the other hand, Barracuda has a completely different process using online delisting tools. Visit each blacklist’s website and follow their specific removal instructions carefully.

5. Monitor and Follow Up

Check daily for removal status and resubmit if necessary. Some blacklists require multiple requests, and removal can take anywhere from hours to weeks.

The removal process can be frustrating. I’ve had cases where it took five separate attempts to get a client delisted because the blacklist operator kept asking for more documentation.

What If Removal Is Denied?

In my experience, if your initial removal request gets rejected, you must make additional improvements to your email practices, wait a few weeks, and then resubmit with a detailed explanation about the steps you’ve followed.

Before we wrap up, let me help you know how to prevent getting blacklisted in the first place to cut down this hassle.

11 Tips on How to Avoid Email Blacklisting

I’ve been helping businesses avoid getting blacklisted for a long time now, let me share those insights here:

1. Start by sending 10 to 20 emails per day. Slowly increase the number each week. This helps build a good sender reputation.
2. Use warm-up tools like TrulyInbox to prepare your email account. This reduces the chance of getting blacklisted.
3. Set up SPF, DKIM, and DMARC records. These help email providers trust your domain and improve delivery.
4. Always use a verified lead list. It reduces the chances of your emails getting sent to spam or being bounced. You can use tools like Saleshandy Lead Finder, Apollo, or UpLead.
5. Clean your email list on a regular basis. Remove emails that are wrong or inactive. If an email bounces hard, delete it. If it soft bounces a few times, remove it too.
6. Add an unsubscribe link in every email. This helps reduce spam complaints and keeps you compliant.
7. Keep your spam rate below 0.1%. This means you are reaching the right people with the right message.
8. Avoid spammy words in your subject line and message. Don’t make it sound too promotional.
9. Use mostly text in your emails, and avoid adding images. This helps your emails reach the inbox.
10. Track your email performance. Check open rates, bounce rates, and spam complaints regularly.
11. Use cold email tools like Saleshandy, Lemlist, or Klenty. These tools help you send emails at scale and protect deliverability.

Protect Your Email Sender Reputation from Day One

In this guide, I’ve covered everything you need to know about email blacklisting. You’ve learned what it is, why it happens, how to fix it, and how to avoid it.

If your domain or email is already blacklisted, don’t worry. Follow the steps I shared to fix the issue and improve your sender reputation.

If you haven’t been blacklisted, that’s even better. Use the tips in this guide to keep your emails landing in the inbox.

If you are starting with a new domain or email account, you can use a tool like TrulyInbox. It helps you warm up your email automatically and mimics real human activity. Give it a try.

FAQs About Email Blacklisting

1. How long does it take to get off an email blacklist?

You can get removed within a day or two. But if the problem is more complex, or the blacklist has a detailed review process, it could take longer.

2. Do all email blacklists work the same?

No, every blacklist has a different criteria for listing and removal. Some blacklists like Spamhaus operate automatically based on user complaints and spam traps, others like SURB undergo manual reviewing and blacklists like Barracuda focus on specific types of threats, such as malware or phishing.

3. What is the difference between IP blacklisting and domain blacklisting?

IP blacklisting affects your email server and sending infrastructure. At the same time, domain blacklisting affects your business’s domain across all email providers, regardless of the IP address used.

4. Can a different email service provider help if I am blacklisted?

Yes, a different email service provider can be very helpful when you’re blacklisted, but it’s not guaranteed. If your email or domain is blacklisted due to spam and other policy violations, then changing the EPS might not resolve the issue.