How can I prevent bot clicks from overwhelming my B2B website after sending emails?
Michael Ko
Co-founder & CEO, Suped
Published 26 May 2025
Updated 17 Aug 2025
6 min read
Sending marketing emails in the B2B space often means your messages land in inboxes protected by advanced security measures. These security systems frequently employ bots or scanners to pre-click links, scan content, and ensure the safety of their users before an actual human interacts with the email. While this is a crucial security function, it can inadvertently lead to a surge of traffic to your website, sometimes overwhelming it and distorting your analytics.
The challenge here isn't just about identifying these bot clicks, but more importantly, preventing them from negatively impacting your website's performance and potentially taking it offline. Understanding the nature of these clicks and implementing robust website-side defenses are key to maintaining both your email deliverability and site stability.
Understanding bot traffic and its impact
Bot traffic to your website after email sends often originates from enterprise-level security systems, such as those used by large corporations and government entities. These are not malicious bots in the traditional sense, but rather automated systems designed to protect recipients from phishing, malware, and spam. They click every link in an email to verify its destination and content before the email ever reaches the recipient's inbox.
It's important to differentiate these good bots from bad bots, like scrapers or DDoS attackers. Blocking these security scanners can have unintended consequences, potentially causing your emails to be flagged as suspicious or spam, thereby hurting your sender reputation and email deliverability. For more on this, you can learn about identifying suspicious bot clicks.
While email service providers (ESPs) like SendGrid may track these clicks, their primary function isn't to shield your website from the resulting traffic. The onus often falls on your website infrastructure and configuration to handle these surges. Understanding what bot traffic is and its potential impact is the first step toward effective mitigation.
Strategies to mitigate website overload
To prevent bot clicks from overwhelming your website, the most effective solutions lie on the web infrastructure side. You want to manage the traffic, not necessarily block the bots entirely, especially if they are legitimate security scanners. Implementing measures that can absorb or filter high volumes of requests without crashing your site is crucial.
One of the most robust solutions is to employ a content delivery network (CDN) or web application firewall (WAF). These services sit in front of your website and are designed to handle massive traffic loads, filter out malicious requests, and distribute legitimate traffic efficiently. They can also implement rate limiting rules, which restrict the number of requests a single IP address (or Autonomous System Number, ASN) can make within a given timeframe.
Using Cloudflare's managed challenge
If you use a service like Cloudflare, you can set up rate limiting rules that trigger a Managed Challenge when an IP address hits a certain request threshold. This typically presents a non-intrusive challenge to suspected bots, while allowing legitimate human users to proceed without interruption. This approach effectively halts bot traffic from overwhelming your site without outright blocking the security scanners, thus preserving email deliverability.
Example rate limiting ruleN/A
if (http.request.uri.path contains "/email-link/") and (cf.threat_score gt 0) then (rate_limit = 100 per 3600s, action = managed_challenge)
Beyond external services, improving your website's fundamental performance is critical. This includes optimizing page load times, using efficient coding practices, and ensuring your hosting infrastructure can scale to handle unexpected traffic spikes. Making your pages cheaper to load for all visitors, including bots, reduces the strain on your servers. For more insights on this, read about mitigating the impact of bot clicks on email marketing metrics.
Advanced bot detection and filtering
While preventing website overload is a priority, isolating and understanding bot clicks can also provide valuable data. This doesn't mean blocking them outright at the email level, but rather using subtle techniques to differentiate bot interactions from human engagement.
One common method is the honeypot technique. This involves embedding a hidden link or field in your email that is invisible to human users but detectable by bots. When a bot clicks this link, it indicates automated activity. Similarly, you can use invisible links to identify bot clicks. These methods allow you to segment bot traffic in your analytics without impacting the legitimate scanning process of security bots. Learn more about honeypot captcha techniques.
Honeypot links in emails
Implementation: Add a link with CSS styling to make it invisible to human readers (e.g., set font size to 1px, match text color to background, or position off-screen).
Detection: If this hidden link is clicked, it's almost certainly a bot. Route these clicks to a low-resource page or a bot-specific endpoint on your server.
Benefit: Allows you to filter bot activity from real engagement data without causing deliverability issues. This helps you to better understand the true performance of your campaigns and learn how honeypots can be used.
Progressive enhancement for humans
Dynamic Content: Serve a basic, lightweight HTML page to all clicks initially. For human users, use JavaScript to progressively load more complex or personalized content after initial page load.
Resource Management: This ensures that even if bots rapidly click, they only consume minimal server resources. Only real human interactions (detected via browser events, CAPTCHA, etc.) trigger the heavier resource usage.
By directing bot clicks to less resource-intensive pages or using a honeypot mechanism, you can absorb the traffic without impacting your primary website's availability or performance. This strategy ensures that legitimate security checks are completed without overwhelming your infrastructure.
Email sending practices to consider
While website-side protections are essential, your email sending practices also play a role in managing bot traffic. Adjusting how you send emails can indirectly help alleviate pressure on your website, especially if you are dealing with a client who is particularly susceptible to being overwhelmed by bot clicks.
Consider the frequency and volume of your email sends. Instead of dispatching a large campaign all at once, spreading out your sends over a longer period can significantly reduce the peak load on your website. This staggered approach allows your server to handle the influx of both human and bot traffic more gradually, preventing sudden spikes that could lead to downtime.
Additionally, assess the number of links within your emails. While a single call-to-action is standard, some emails might include numerous links. Reducing the overall number of clickable elements can diminish the total volume of bot-initiated requests. Focus on a clear primary call to action to not only improve user experience but also reduce unnecessary bot activity. For tips on improving email engagement, explore how to increase email click through rate.
Balancing deliverability and website stability
Navigating the complexities of bot clicks in B2B email marketing requires a multi-faceted strategy. It is not just about identifying the bots but implementing solutions that protect your website's integrity while maintaining positive email deliverability.
By focusing on robust website infrastructure, intelligent traffic management tools like CDNs and WAFs, and refining your email sending practices, you can effectively prevent bot clicks from overwhelming your B2B website. Remember, these are often good bots performing necessary security functions. The goal is to accommodate their legitimate activity without compromising your website's performance.
Views from the trenches
Best practices
Use a CDN/WAF to absorb traffic spikes and implement rate limiting rules on your website. Configure challenges for high request rates from single IPs or ASNs.
Optimize your website's performance to reduce page load costs. Lightweight landing pages for email links can significantly help.
Spread out your email send times to avoid sudden, overwhelming traffic surges from bot pre-fetching.
Common pitfalls
Completely blocking IP ranges associated with security scanners, as this can negatively impact email deliverability by flagging your emails as suspicious.
Relying solely on your ESP's bot filtering, as it often only affects reporting and doesn't protect your website's infrastructure.
Ignoring website performance issues, which makes your site vulnerable to even legitimate bot traffic volume.
Expert tips
If the site is constantly going down, a rate-limited managed challenge can be a good immediate patch to prevent outages.
Sometimes, enterprise inboxes generate huge surges of bot activity. Identifying and rate-limiting only those specific Autonomous System Numbers (ASNs) can be effective.
A longer-term solution involves improving the website's ability to handle traffic or making content cheaper to generate for all visitors.
Marketer view
Andrew from Email Geeks says they use invisible links or 1x1 pixels to capture bot clicks and differentiate them from real user engagement.
2025-01-14 - Email Geeks
Marketer view
If the website can't handle traffic spikes, a temporary fix might be to link to less resource-intensive pages or send emails more slowly.
Cloudflare, you can set up rate limiting rules that trigger a Managed Challenge when an IP address hits a certain request threshold. This typically presents a non-intrusive challenge to suspected bots, while allowing legitimate human users to proceed without interruption. This approach effectively halts bot traffic from overwhelming your site without outright blocking the security scanners, thus preserving email deliverability.
