Interserver blacklist: Step-by-step guide to check, prevent and remove

Yes, getting listed on the Interserver blacklist can disrupt your email deliverability, blocking your messages and hurting your reputation. But the good news? Fixing it is manageable with the right approach.

In this article, you will for sure find some tips to check if your domain or IP is blacklisted, prevent future issues with smart email practices, and even remove your listing if you’ve been flagged. Let’s go!

What is the Interserver blacklist and how does it work? 

The Interserver blacklist is a DNS-based system that flags IP addresses and IP ranges associated with spammy or harmful email activity. That’s it. 

In simple terms, it’s designed to protect email users by identifying servers sending unsolicited bulk emails, hitting spam traps, or exhibiting patterns consistent with malicious behavior.

How does it work? When an email is sent, the recipient's server checks the sender's IP address against the Interserver blacklist using DNS queries. So if the IP is listed, the email may go to spam, be rejected, or blocked entirely. In fact, the blacklist can target individual IPs or entire ranges if a larger issue is detected.

Here’s a simplified look at how DNS-based blacklists function:

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Why do IPs get blacklisted? Interserver flags IPs for several key reasons:

• Sending unsolicited bulk emails.
• Poor email list hygiene, leading to hits on spam traps.
• Compromised servers being used to send spam.
• Misconfigured email authentication protocols (SPF, DKIM, DMARC).

So here are some warning signs you’re at risk of being blacklisted:

• High bounce rates from your email campaigns.
• An increase in spam complaints from recipients.
• Sharp declines in email open and engagement rates.
• Rejected emails with bounce-back messages mentioning blacklists.

📌 What’s next? Start by testing your deliverability and pinpointing issues with MailReach’s Email Spam Test. It shows where your emails land and highlights what’s causing problems. Blacklist or not, this tool gives you the insights you need to fix your email performance and keep hitting the inbox.

👉 Run a spam test with MailReach today

How to check if you're on the Interserver blacklist ?

1. Use Interserver’s blacklist lookup

Interserver offers a simple way to check your status. Visit their DNSBL Lookup Tool, enter your IP address or domain, and submit the form. No other steps required! 

If you’re listed, the tool will quickly provide a clear result, along with the reason for the listing (e.g., spam complaints, suspicious activity). You’re welcome. 

2. Use MxToolbox for a broader scan

For a more comprehensive check, head over to MxToolbox Blacklist Check. Enter your IP address or domain, and it will scan your status across multiple blacklists, including Interserver. The report will tell you if you’re listed, along with details about each relevant blacklist.

What to do if you're listed

If the results confirm you’re blacklisted, don’t panic. Interserver provides a clear path for removal (covered in the next section). Before proceeding, identify and fix any issues that caused the listing, such as misconfigured DNS records, compromised email accounts, or sending to spam traps.

The bigger picture: Being blacklisted might sound like the end of the road, but the real problem lies in your deliverability performance. Knowing whether your emails land in inboxes or spam is far more important than obsessing over a blacklist. Trust us.

Your top priority is to check where your emails land

Here’s the truth: most external blacklists, including Interserver, have minimal impact on deliverability when it comes to major providers like Google and Microsoft, which dominate the email market. What truly matters is where your emails end up, whether that’s the inbox or the spam folder. Everything else? It’s just noise.

If you want to improve your email performance, you need to check how your deliverability stacks up and fix any problems that might be keeping your messages out of the inbox.

That’s where MailReach’s free email spam test becomes really interesting and helpful. Unlike most tools giving you vague or incomplete results, MailReach provides a detailed report on your real inbox placement. The result? All you need to do is send a test email (under your normal sending conditions) to 30 test inboxes provided by MailReach. In return, you’ll get a full breakdown of your deliverability, a score out of 10, and specific recommendations for improvement. And that’s it.

This includes insights into your content, spam triggers, DNS configurations, blacklist checks and more!

So yes, check if your IP is blacklisted with tools like MxToolbox, but don’t stop there. The real win is ensuring your emails reach their destination, and MailReach is the tool to make that happen. Start your spam test today!

Removing your IP from the Interserver blacklist

If your IP has landed on the Interserver blacklist, here’s exactly how to get it removed:

1. Identify and fix the problem: Before anything else, figure out why your IP was blacklisted, as common reasons include sending spam, compromised accounts, or misconfigured email settings. Then, clean up any malware, secure your systems, and ensure your email practices are up to standard. First step: done!
2. Check if your IP is still blacklisted: You need to know that Interserver often automatically removes IPs after a set period (usually 7 days) if no further spam is detected. Verify your status using tools like MxToolbox, and you will maybe have a good surprise.
3. Submit a delisting request: If you're still listed, go directly to the Interserver Blacklist Removal page. Enter your IP address and provide any required details. And please, be honest and concise about the steps you've taken to resolve the issue.
4. Implement proper email authentication: Set up SPF, DKIM, and DMARC records correctly. Why? Because these protocols are made to authenticate your emails, making you a trusted sender in the eyes of email providers. Precious? Yes, yes and yes. 
5. Maintain consistent sending patterns: We keep repeating this, but you must avoid any sudden spikes in your email sending volume, as consistency builds a positive sender reputation.
6. Monitor your email deliverability: Our final tip is to regularly check your IP and domain reputation with tools like MailReach’s Email Spam Test, especially to see where your emails land and catch issues early.

📌 Here are some key takeaways:

• Act fast to resolve the root cause.
• Use Interserver's official removal process for quicker delisting.
• Keep your email practices clean to prevent future blacklisting

Prevention strategies: keeping your IP off the Interserver

Even if it seems too simple to be true, avoiding the Interserver blacklist is all about maintaining a clean sender reputation. Here’s how to keep your IP safe:

• Verify your email lists: Always send to clean, engaged email lists, and think about using verification tools to remove invalid addresses, typos, and spam traps before launching campaigns. 
• Manage your sending volume: Again, avoid large spikes in email volume, especially from a new IP. Instead, just gradually scale your sending to establish credibility with email providers and this will be enough. 
• Follow content guidelines: Your email content must not trigger spam filters, so don’t use overusing promotional words (e.g., “free,” “urgent”), also known as spam words, or include excessive links and images.

Need clearer information? Here a comparison table for good vs. bad email practices: 

The role of email warmup in preventing blacklisting

Let’s be clear: email warmup doesn’t guarantee protection from blacklisting, but it does play an important role in building the reputation needed to avoid behaviors that lead to blacklisting. 

Here’s how it works: email warmup gradually increases your sending volume while creating positive engagement signals, even if it’s not only about that. The whole point of this approach is to reduce the risk of being flagged for spammy or suspicious behavior, so of being blacklisted.

Good to know: MailReach’s email warmup service is tailored specifically for B2B senders. How? Simply by automating the process of building trust with email providers when sending low-volume and authentic interactions through your domain. Coupled with MailReach’s Spam Checker, you gain a strong insight into your deliverability, ensuring your setup, content, and email lists aren’t putting you at risk of ending up in spam (or worse, on a blacklist).

The real takeaway? Blacklist or no blacklist, what matters is landing in the inbox. 

👉 Start building your sender reputation with MailReach’s email warmup service today!