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what happens if my IP is blacklisted
SrushtiFeb 28, 2024 9:34:29 PM12 min read

What Happens if my IP is Blacklisted?

From time to time, online business owners and email marketers may find that traffic to their pages or the deliverability of their emails begins to fall for no discernible reason. Of course, several factors could be contributing to these issues, from search engine indexing problems to server-based complications. But sometimes marketers may wonder, is my IP blacklisted?

IP blacklisting is a common cybersecurity tactic intended to prevent malicious entities from accessing private networks via fraudulent or spam emails. Organizations will set up systems designed to monitor communications between the host’s private network and all external IP addresses, flagging any IPs thought to be sending suspicious or unusual volumes of emails.

Email service providers like Google and Microsoft can gain access to these blacklists, with options to automatically categorize messages associated with flagged IPs as junk or spam in their account holders’ inboxes. Typically, the owners of blacklisted IPs will notice a significant drop in email deliverability, negatively affecting the source’s reputation and marketing efforts.

While IP blacklisting is mostly beneficial to the safety of online businesses, consumers and sensitive digital information, occasionally IPs can be incorrectly flagged as malicious. To help marketers better understand this sometimes complicated issue, below is a detailed guide outlining how to identify, address and prevent your IP address being accidentally blacklisted.

Table of Contents

The Consequences of a Blacklisted IP

Holders of IP addresses can use a number of different methods to discern whether their IP may have been blacklisted by one or more entities. While many may assume email service providers receive IP blacklist data from one centralized source, there are actually multiple IP blacklists currently in operation, with some lists causing more harm to IP holders than others.

The most credible IP blacklists known to negatively affect email deliverability are:

  • Spamhaus
  • SpamCop
  • Barracuda
  • Domain Name System Blacklist (DNSBL)
  • Passive Spam Block List (PSBL)
  • Invaluement

For email marketers wondering, is my IP blacklisted? The simplest way to check is to locate your email server’s IP address and enter this value into one or more of the above IP blacklist sites. Search results will indicate whether these services have flagged your IP as suspicious.

Assuming your IP has been blacklisted by a credible source, likely consequences include:

Impaired email deliverability

Emails sent from blacklisted IP addresses are far more likely to be blocked outright by email and internet service providers. IP address holders will usually receive a bounce message shortly after sending correspondence from a blacklisted IP, including both the name and the URL of the relevant blacklisting service. However, even if no such message is received, your IP may still be registered on a blacklist despite this factor not currently affecting deliverability.

High chance of emails marked as spam

Emails sent from blacklisted IP addresses have a high chance of being sent directly to spam or junk folders in linked recipients’ accounts. If an email service provider such as Microsoft or Google believes your IP address is registered with a credible blacklisting service, it’s highly likely that any emails you send to their customers will be automatically flagged as spam.

Significant reputational damage

Companies associated with blacklisted IPs can suffer significant reputational damage, as all emails sent from official accounts will be at risk of being marked as suspicious. If customers associate your brand with spam, your company’s credibility and reputation will be adversely affected, with 70% of email users believing spam negatively impacts their online experience.

Wider business communication issues

Emails sent from blacklisted IP addresses are not only less likely to reach potential clients, but may also be sent to junk mail inboxes associated with existing customers and internal employees. At present, it’s believed around 61% of internet users deploy some form of spam filter intended to automatically block suspicious emails, potentially hindering wider business communications for any entities that find their IP address wrongfully linked to an IP blacklist.

Common Reasons for IP blacklisting

While different IP blacklisting services typically have their own set of criteria for determining suspicious accounts (many of which are not openly publicized), some common reasons are widely recognized by digital communications experts. For marketers wondering, is my IP blacklisted? It can help to consider whether the following factors apply to your IP address.

Spam emailing behaviors

Email marketers that frequently send out large numbers of similar messages to multiple unrelated accounts may be at risk of being flagged as suspicious entities. If IP blacklisting services take notice of this behavior, or if a large number of recipients manually flag your messages as junk in their own accounts, the likelihood of your IP being blacklisted will rise.

Common examples of spam-like behavior in the eyes of IP blacklisting services include:

  • Sudden increases in send volume:  If your send list is extended significantly in a short period of time service providers and blacklisting sites will see this as suspicious.
  • Links to suspicious sites in emails: Alongside IP addresses, website domains can also be found on blacklists. Sharing links to sites currently registered on blacklists in the body of your emails can lead blacklist operators to associate your IP with fraud.
  • Exceeding common sending limits: Most email vendors will set a daily limit on the number of messages that can be sent from a single account, typically between 500 - 1,000. Exceeding this limit can lead providers to associate IPs with fraudulent activity.

Emails sent to invalid addresses

If organizations are found to be sending large numbers of messages to invalid or otherwise inactive email addresses, providers may flag associated IPs as suspicious. If recipients do not open your messages, or your emails are frequently bounced from intended addresses, these actions can signify spam-like behavior. This can cause your IP to be blacklisted. For marketers to avoid this, it’s wise to vet all newly acquired mailing lists for inactive accounts.

Email server misconfiguration

There are several authentication protocols that email marketers must set up to prevent email server misconfigurations enabling illegitimate sources to spoof their accounts. If protocols like DKIM, SPF and DMARC are not updated, fraudulent entities may be able to send spam emails from otherwise legitimate IP addresses, increasing the risk of IP address blacklisting.

Cybersecurity vulnerabilities

Blacklisting service operators are known to monitor the internet in search of IP addresses associated with malware, phishing scams and data breaches. If an organization’s websites or email accounts are not suitably secured behind multi-factor authentication protocols and related cybersecurity tools, they may be vulnerable to hacking activity leading to blacklisting.

Additionally, during processes such as cloud data warehouse migration, it's crucial to ensure that sensitive data remains secure and that the migration itself doesn't inadvertently expose your IP to potential blacklisting risks.

How to detect IP blacklisting

No matter whether you have reason to believe your IP has been blacklisted or not, via things like unusual website traffic drops or impaired email deliverability, it’s wise to frequently check blacklists for your IP address. The main reason for this being that compromised addresses do not always instantly impact operations, so rectifying issues early can save your credibility.

How to monitor IP reputation

The reputation of your IP address among internet and email service providers determines the deliverability of your messages. If your reputation is poor, it’s more likely that your emails will be flagged as spam. Thankfully, there are a number of ways to reliably monitor your IP reputation, provided you know how to find the IP address data associated with your account.

To find your IP address, simply open any message sent via your email service provider and navigate to the message header. Here, you should find a section labeled “Received-SPF” or “Authentication-Results”, the following 12 digits formatted as follows will be your IP address:

With this information to hand, it’s possible to use a number of online IP checker tools to view your IP reputation among service providers. Credible IP reputation checker services include:

  • Sender Score
  • Talos
  • Reputation Authority
  • Trusted Source
  • Barracuda Central

How to check if your IP is blacklisted

Alongside regularly monitoring your IP reputation, it’s important to check IP blacklisting sites to discern whether your address is currently registered as suspicious. For email marketers wondering, is my IP blacklisted? Try inputting your IP address into one of the following tools:

  • MXToolbox
  • Barracuda
  • DNS Checker

How to remediate a blacklisted IP

If any previously mentioned IP monitoring or blacklist checking tools suggest your IP may be blacklisted, it’s important to begin tackling the problem immediately to mitigate any loss of credibility. To aid teams in this task, below is a step-by-step guide to IP blacklist remediation.

1. Find the source of the problem

Most blacklist operators will require IP address holders to fix identified issues before their IPs will be considered for removal. To do this, organizations must be able to quickly work out the likely cause of their problem. The simplest way to achieve this is to run your IP through a few credible IP checkers and review the listed reasons for blacklisting across multiple services.

While it’s common for IP checking tools to give a likely reason for blacklisting rather than a definitive answer, cross-referencing results from multiple sites will narrow down your search.

2. Clean up your mailing lists

If your IP checking process returns a likely cause related to undeliverable emails, messages sent to invalid addresses or a high frequency of mail self-reported as spam, cleaning your email list can help to fix the problem. Review your email list to locate and remove accounts that don't open your emails, alongside any addresses from which emails are often bounced. Also, make it easy for recipients to unsubscribe from your lists to reduce self-reported spam.

3. Resolve any technical issues

If IP blacklisting checks suggest technical issues may be the root cause of your problem, it can be wise to begin rectifying common server-based issues. Inconsistencies found in DNS records and SMTP banners may result in your IP being blacklisted, alongside the presence of viruses or malware. So scan for and fix these issues before requesting blacklist removal.

4. Request removal from blacklists

As soon as you’re confident that the root cause of your IP blacklisting problem has been resolved, you’ll be ready to formally request the removal of your IP from relevant blacklists. This task can differ slightly depending on whether the blacklist is self-serviced or automated.

  • Self-serviced: Visit the official site of the blacklisting service and fill out their internal form to request blacklist removal. You’ll need to offer a detailed explanation covering why your IP was flagged as suspicious, and provide evidence that the issue is fixed, a representative will then review your case and respond to your request accordingly.
  • Automated: Follow the same process as above, though rather than waiting for a response from a representative, check the blacklist in 1-2 weeks to confirm removal.

How to prevent future IP blacklisting

Unfortunately, successfully removing your IP address from blacklisting pages will not ensure that your IP is not blacklisted again in the future. To prevent this, organizations must commit to a number of smart policies and best practices designed to mitigate the risk of blacklisting.

If you want to stop asking, is my IP blacklisted? Take note of the following best practices.

Set up a dedicated email IP address

Organizations that use shared email IP addresses may experience reputational problems as a result of the poor practices of unassociated senders. While setting up a private email IP address can be expensive, doing so will offer companies more control over their reputation.

Stay informed about emerging threats

Continuously monitor logs for IP addresses associated with known malicious activity or blacklisted sources. This could include integrating threat intelligence feeds into your logging solution to automatically flag suspicious IPs.

Adhere to mass email best practices

Mass emailing is commonly associated with unwanted spam and fraudulent activity in the eyes of internet service providers, though for email marketers, this process is a necessity. To prevent your campaigns from being seen as suspicious, stick to the following best practices:

  • Frequently update and review your email lists, check for any addresses that regularly return bounce messages or seem to be flagged as invalid, remove them from all lists.
  • Review your DNS accounts, check your email authentication measures like DMARC, SPF AND DKIM are up to date and accurate, and enact plans to perform regular checks.
  • Make email unsubscription options clearly viewable to recipients, doing so will greatly reduce the likelihood of internet-users flagging your messages as spam.
  • Avoid overusing spam-triggering words or phrases in your emails, common examples include “cash”, “be your own boss”, “giveaway”, “once in a lifetime” and “promotion”. When utilizing an email copy generator, ensure it helps you strike the right balance in crafting engaging content without inadvertently triggering spam filters.
  • Don’t include large numbers of links in the body of your emails, and avoid linking to blacklisted sites, check all links prior to inclusion to prevent accidental IP blacklisting

Regularly review your IP reputation

Enact plans to regularly monitor and maintain your IP reputation, beginning by searching for your IP using reputable IP checker tools on a weekly basis. Assign this responsibility to one or more members of your team and compile findings in an ongoing report for regular review.

Commit to continuous staff training

Train all members of your organization in how to follow email best practices and review their work for potential indicators of spam. Create guides detailing common spam-triggering words, lists of known blacklisted sites and methods of checking for invalid email addresses. Make these guides easily accessible on internal systems and host regular training sessions.


IP blacklisting is a surprisingly common problem that can significantly impact the credibility of email marketers and commercial organizations. If internet or email service providers view your IP address as suspicious, it’s highly likely your campaigns will become undeliverable.

IP blacklisting services use a number of methods to determine whether IPs are suspicious, with the intention to stop spam and malware from impacting internet users. However, some legitimate IPs can be wrongfully blacklisted if best practices are not followed. To prevent IP blacklisting, emails and email lists must be regularly reviewed in search of common issues.

To stop marketers wondering, is my IP blacklisted? Avoid the use of spam-triggering words, frequently review your IP reputation, regularly update your email authentication measures and commit to continuous staff training. With these tips in mind, blacklisting can be avoided.

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Srushti Shah is an ambitious, passionate, and out-of-the-box thinking woman having vast exposure in Digital Marketing. Her key focus is to serve her clients with the latest innovation in her field leading to fast and effective results. Working beyond expectations and delivering the best possible results in her professional motto. Other than work, she loves traveling, exploring new things, and spending quality time with family. Reach out to Srushti Shah on Twitter or LinkedIn