What to do if your shared IP is on a Barracuda blacklist?
Michael Ko
Co-founder & CEO, Suped
Published 24 Apr 2025
Updated 19 Aug 2025
6 min read
Discovering your shared IP address on a Barracuda blacklist (or blocklist) can be a frustrating experience, especially when your email sending patterns haven't changed. It often leads to a sudden increase in hard bounces and a noticeable disruption in your email deliverability. This situation is particularly common with shared IPs because the actions of other senders on the same IP can directly impact your reputation, even if your own sending practices are impeccable.
Unlike some other blacklists that might delist an IP automatically after a few days of clean sending, Barracuda often requires a manual removal request. This makes the process a bit more hands-on and requires a clear understanding of the steps to take.
The first step is to confirm that your shared IP address is indeed listed on the Barracuda Reputation Block List (BRBL). You can do this by using the Barracuda Central lookup tool. Simply enter your IP address to check its current status and see if it's flagged.
Once confirmed, it's crucial to understand why the listing occurred. While it might feel like a random event, especially on a shared IP, Barracuda's system typically reacts to specific types of suspicious email activity. This could range from sending spam, hitting spam traps, or even having compromised accounts on the shared IP. For more details on how these types of blocklists function, you can review how email blacklists actually work.
It's worth noting that Barracuda sometimes implements broader IP blocks that can affect a wide range of users, regardless of individual sending practices. There was a notable instance in June 2019 where many email service providers saw an uptick in Barracuda listings, which wasn't tied to specific user actions. Understanding these patterns can help alleviate immediate concern, but the need for delisting remains.
Shared IP versus dedicated IP responsibilities
For users on a shared IP address, the primary responsibility for delisting typically falls on your email service provider (ESP). Your ESP manages the shared infrastructure and is in the best position to address the underlying issues that led to the block. They have direct channels to blacklists like Barracuda and can provide the necessary context and assurances for removal.
When you're dealing with a shared IP, your email deliverability is intrinsically linked to the reputation of all other senders using that same IP. If one sender engages in practices that Barracuda deems suspicious, the entire IP can suffer. This is a common challenge for those using shared sending pools, and it highlights why it's so important to choose an ESP with robust abuse prevention measures.
While you might be tempted to submit a delisting request yourself, your ESP is usually better equipped. They can verify that any issues have been resolved, ensuring that the IP will remain clean after delisting. If you manage your own dedicated IP, the responsibility for delisting is solely yours. For more information on what happens when your IP gets blocklisted, a comprehensive guide is available.
Action plan for delisting
The most effective course of action is to immediately notify your ESP about the Barracuda blocklist listing. Provide them with your sending IP address, the bounce messages you're receiving (especially those referencing Barracuda), and any other relevant details about the issue. They should have a process in place for handling such incidents.
Your ESP will investigate the root cause, which could involve identifying the specific sender on the shared IP responsible for the problematic activity or confirming a broader, systemic issue with Barracuda. Once they've addressed the cause, they will submit the official delisting request to Barracuda Central. In some cases, directly emailing intent@barracuda.com can also expedite the process once the issue is resolved.
Barracuda's delisting process generally involves filling out a form on their Barracuda Central website. The ESP will typically handle this, providing the necessary information about the IP and the steps taken to resolve any underlying issues. After submission, monitoring the IP's status is important to confirm successful delisting. This process might be part of a broader strategy to resolve Barracuda blocklist issues.
While your ESP works on the delisting, consider auditing your own email practices. Even on a shared IP, maintaining clean lists, sending relevant content, and authenticating your emails properly can contribute to better overall reputation and minimize your impact on the shared IP. Implementing authentication like DMARC, SPF, and DKIM can help prove your legitimacy.
Preventative measures and best practices
To prevent future blocklistings (or blacklistings), especially on shared IPs, consistent vigilance is key. This includes regularly monitoring your sending reputation and adhering to email marketing best practices. A proactive approach significantly reduces the likelihood of deliverability issues.
Ensuring your email lists are clean and regularly updated is paramount. Sending to invalid or inactive addresses can lead to high bounce rates and spam trap hits, which are major triggers for blocklists. Employing double opt-in for new subscribers and regularly removing unengaged contacts helps maintain a healthy list.
Maintaining high engagement rates is another crucial factor. Emails that consistently receive opens and clicks signal to ISPs and blocklist providers that your content is valued. Conversely, low engagement can indicate that your emails are unwanted, leading to higher spam complaints and potential blocklistings.
Views from the trenches
Best practices
Maintain a clean email list by regularly removing inactive or bounced addresses to improve sender reputation and prevent blocklistings.
Segment your audience and personalize content to increase engagement, reducing the likelihood of spam complaints.
Implement email authentication protocols like SPF, DKIM, and DMARC to verify your sending legitimacy and prevent spoofing.
Monitor your email deliverability metrics and regularly check your IP and domain against major blacklists.
Common pitfalls
Failing to notify your ESP immediately after discovering a blacklist listing, delaying the resolution process.
Sending emails to purchased or old, unverified lists, which can lead to high bounce rates and spam trap hits.
Ignoring recurring deliverability warnings or low engagement metrics that indicate potential underlying issues.
Trying to manually delist an IP without understanding the root cause, leading to repeated blocklistings.
Expert tips
For shared IPs, collaborate closely with your ESP, as they often have direct channels and expertise to resolve blocklist issues efficiently.
Understand that some Barracuda listings may be part of broader, systemic issues affecting many ESPs, not just your specific sending.
Keep records of bounce messages, as they often contain valuable information about the specific blocklist and reason.
Focus on consistent, high-quality email practices to build a strong sender reputation, minimizing vulnerability to future listings.
Marketer view
Marketer from Email Geeks says: Customers have had issues with Pardot placing them on shared IP addresses with blacklisted senders, requiring external deliverability specialists to resolve.
2019-06-18 - Email Geeks
Marketer view
Marketer from Email Geeks says: Across nearly all ESPs, there was an unexpected rise in Barracuda listings with no clear cause, making it difficult to understand the reason behind the blocks.
2019-06-18 - Email Geeks
Navigating barracuda blocklists on shared IPs
Dealing with a Barracuda blacklist on a shared IP can be challenging, but it's a manageable issue when approached correctly. The key takeaway is that your ESP plays a critical role in resolving these types of blocklistings. Leverage their expertise and communication channels to expedite the removal process.
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