Are you on the front line fighting the good fight against bots? Fear not. In this article, we’ve put together the strategies and resources you need to gear up against Klaviyo list bombing.
If you are an eCommerce store owner who uses Klaviyo, it might not be the first time you experience such an attack. List bombing is when bots or malicious actors submit fake or compromised email addresses in bulk—often resulting in thousands of spam email sign-ups to your business’s newsletters.
An increase in subscribers usually brings joy to an online store owner, but this is not the case with a hostile attack. Klaviyo list bombing poses a threat as it can lead to increased bounce rates, higher spam complaints, and inflated costs. Moreover, your email program could be used to harass people without your knowledge.
Prevention and mitigation strategies against list bombing are crucial. Keep reading to understand the purpose and impact of list bombing, and how to minimise the damage caused by attacks.
The Purpose Behind Klaviyo List Bombing
What is the purpose of attackers that use Klaviyo list bombing? First, a quick note on bots vs. the attackers behind them.
When we think of bots, we usually think of the ones that cause attacks. But bots are just automated software applications running tasks, and many bots provide good services. However, the bots we’re referring to in this article are not beneficial. The people behind these kinds of bots can be scammers, fraudsters, hackers, or other malicious actors.
These attackers can aim to test stolen email addresses. They might collect email addresses from data breaches or social media. They then subscribe the victim’s email address to thousands of mailing lists and newsletters, flooding the victim's inbox. This can be done to harass the victim or distract them from targeted phishing or fraud attacks.
Klaviyo list bombing can also disrupt a business's operations. It overloads systems and causes slowdowns or even crashes.
How Does Klaviyo List Bombing Affect Your Business?
Email Deliverability Issues
One of the immediate impacts of Klaviyo list bombing on your business relates to email deliverability. List bombing can lead to an influx of spam reports. As a result, email service providers (ESPs), such as Klaviyo, could flag your brand's emails as spam. Your brand’s email domain could be blacklisted and viewed as suspicious by both ESPs and ISPs (internet service providers).
The result? Instead of reaching your genuine subscribers, your emails may land in spam folders or not be delivered at all.
Klaviyo List Bombing Impact on Email Marketing
Another direct impact is that Klaviyo list bombing increases hard bounce rates. A hard bounce is when an email can’t be delivered for a permanent reason, such as when the email address is invalid or doesn’t exist. Higher bounce rates negatively affect your sender's reputation.
Your sender reputation is also hurt when you consistently send emails to unengaged or fake subscribers. As mentioned, sending emails to people who did not genuinely subscribe to your brand can lead to spam complaints, harming your reputation.
Increased Costs
Last but not least, Klaviyo list bombing can cost you. Many email marketing platforms, such as Klaviyo, charge based on your subscriber count. This means you’re actually paying money for the fake entries from a list bombing. This inflates costs and is, in essence, money down the drain.
List bombings can also increase operational costs. Your customer support team might receive a large number of complaints about unwanted emails, and you might have to deal with a spike in unsubscribe requests. Handling these issues can require more resources than normal.
Signs of a Klaviyo List Bombing Attack
Sudden Spike in Subscriber Numbers
A clear first indicator that you’re under attack is a sudden, significant spike in subscribers. Naturally, if you have recently undertaken a list growth campaign, a spike can be a cause for celebration. However, it doesn’t hurt to watch out for suspicious spikes even under such circumstances.
If you have identified an unexpected increase in sign-ups, examine these recent subscribers for anything shady. For example, you can keep tabs on the following patterns of list bombing entries:
- A large number of sign-ups at a specific timeframe
- A large number of subscribers from the same sign-up form
- A large number of submissions coming from the same IP source
Unusual Email Domains
Apart from the above trends, you also want to beware of dodgy email domains or addresses. Some unusual email addresses are clearly gibberish, while others are generic. An example is xyz123 @ spam.com. If several sign-up addresses are unusual and make you suspicious, act on your instinct.
Another red flag is if a large number of recent sign-ups all come from the same domain, for example, if they’re all from @spam.com. Apart from the email domain, it also doesn’t hurt to take a look at the contact name. If the first and last name of the contact name are gibberish, it’s another reason to take a closer look.
High Bounce Rates and Spam Complaints
As mentioned, Klaviyo list bombing can lead to higher bounce rates. Emails can, of course, bounce due to other reasons. Subscribers might accidentally register with an incorrect email address, leading to opt-in email bouncing. However, if you detect a spike in bounce rates, it is a potential sign of an attack.
The same goes for spam complaints about your emails. A sudden influx of spam reports can also result from list bombing, which signals something isn’t quite right.
Anomalies in Click Tracking
Another potential sign of Klaviyo list bombing is if you find discrepancies in your click tracking. This may indicate bot activity, as your click rates take a hit when your subscriber list is inflated. It’s wise, therefore, not to ignore any anomalies in your click tracking data.
Preventive Measures for Klaviyo List Bombing
Next, let’s look at some strategies and resources to help you fight the bots.
Dedicated Click Tracking
The first preventive measure you can take is to set up dedicated click tracking with SSL. This means that you implement tracking using your own domain instead of Klaviyo’s default encoding.
One main benefit is reduced bot clicks. Your links will also appear more legitimate to email filters, which leads to improved deliverability. Another benefit is increased customer engagement. As your tracking links display your own domain—a domain your customer is familiar with—your links look more recognisable and trustworthy.
Bot Protection Strategies
The next step is to safeguard your metrics. You can do this by creating a “remediation” segment to suppress potential bots and fake profiles. As segment criteria, you can focus on recipients with low engagement, such as those who have received emails but have never opened an email, clicked a link, viewed a product, started checkout, or made a purchase.
You can use segmentation with the rule “Click bots = false”. This allows you to distinguish between bot and human clicks, filtering out bot activity without excluding valuable profiles. A pro tip is to avoid creating an exclusion segment of “Bot Click = True”.
When you view your metrics, you want to exclude the segment with bots. Excluding bots from attribution and reporting ensures your data won’t be skewed. Make sure to update attribution settings to exclude bot clicks from email and SMS reports and Apple Privacy Protection opens.
Enable Double Opt-in for Sign-ups
Another preventative step to mitigate a Klaviyo list bombing is enabling double opt-in (DOI). Double opt-in means that a confirmation email is sent to each address after a sign-up. It requires your subscribers to confirm their email address before joining your list, ensuring that they genuinely want to receive your communications.
DOI cannot prevent a list bombing, but it can ensure that the addresses don’t make it to your main lists. Recipients who never genuinely signed up will only receive one double opt-in email from you.
Add CAPTCHA Challenges to Sign-up Forms
Most of us have likely complained about an annoying CAPTCHA, having to painstakingly choose boxes with traffic lights to prove we are not bots. But the truth is, adding a CAPTCHA to your sign-up form is a great way to help deter bots.
These CAPTCHA challenges help differentiate between human users and bots. By stopping malicious sign-ups at the source, they can significantly lower the risk of Klaviyo list bombing.
But what about the fact that CAPTCHA challenges can frustrate subscribers? Fortunately, CAPTCHAs have come a long way. Klaviyo allows integration with Google’s user-friendly ReCAPTCHA. It has a “I am not a robot” checkbox, which is simple for subscribers to pass and can deter automated mass submissions.
Monitor Sign-up Sources and Set Up Alerts for Unusual Activity
Even if you have implemented the strategies above, it is wise to keep monitoring sign-up sources. You’ll want to track where subscribers come from to identify any unusual activity.
It’s possible to find known spam domains and IPs on certain platforms, and then block them. If a specific domain or IP address consistently leads to spam reports, you can add it to your blocklist.
You can also set up automated alerts for unusual subscriber activity. For example, you can set up an alert that notifies you when there's a sudden increase in sign-ups in a short period. This allows you to investigate and address potential Klaviyo list bombing quickly.
Regularly Cleanse Your Email List
Using best practices to keep your email list clean is also wise. Conduct regular audits of your lists, where you remove inactive, invalid, or suspicious email addresses.
This kind of regular list hygiene helps you maintain a high-quality subscriber base. It also improves deliverability, reduces bounce rates, and helps safeguard sender reputation over time.
How to Respond If Your List Is Bombed
Immediate Actions
If you have become the victim of a Klaviyo list bombing—don’t panic! An immediate action you should take is to pause email campaigns. Temporarily halting emails helps prevent further damage to your sender reputation.
Identify and Remove Fake Emails
The next step is to use Klaviyo’s tools to detect and delete invalid or malicious email addresses. Analyse the trends with the new subscriptions that have come in, take these data points and create a segment to identify fake profiles.
Seek Support
Don’t be afraid to ask for help! Contact Klaviyo’s support team for assistance in mitigating the attack's impact. You can also reach out to support for help building a segment to capture profiles and restoring list integrity.
Review and Audit
After a Klaviyo list bombing, it’s also a good time to audit security settings. You might want to review and reassess your settings and implement stricter protection. Keep monitoring ongoing activity and update form protections accordingly.
Long-Term Strategies to Safeguard Your Email List
Restrict Public Sign-Up Forms
Naturally, as an eCommerce store owner, you’re interested in strategies that will protect your email list and business in the long run. One long-term strategy is to limit exposure by controlling where and how your forms are displayed. If possible, restrict the locations of your forms, such as public sign-up forms, or add a human verification process.
Implement Advanced Validation Tools
You can also invest in a third-party solution to verify email addresses at the point of sign-up. Advanced validation tools can also be implemented. They can run a series of tests to determine the probability that an email address is valid and safe.
Educate Your Team
Educating your team on bot attacks is definitely a worthy investment. You want to communicate with everyone involved in email marketing. Make sure they understand the risks and signs of Klaviyo list bombing and the importance of robust security measures.
Continuous Monitoring
Monitoring is always key. Regularly review your analytics to spot and address suspicious activity early. As mentioned, you can monitor bot clicks through segmentation. You can also analyse data in Klaviyo’s Metrics tab. Creating custom deep dive reports in Klaviyo to find data around bot clicks is also possible.
Conclusion: Implement Security Features to Protect Your Klaviyo Lists
Addressing Klaviyo list bombing and its potential impact on email marketing is critical for Klaviyo users. If you’re not on guard, bot attacks can lead to decreased email deliverability, increased bounce rates, and even inflated costs. It is vital to stay vigilant when it comes to preventative measures, swift response strategies, and long-term tactics.
Keep monitoring and reviewing your current email sign-up processes. Don’t hesitate to implement the security features discussed to protect your lists. If you do so, you can be sure you’ve done everything in your power to gear up against Klaviyo list bombing.
