Why do ad blockers sometimes block non-advertising content?

Ad blockers can inadvertently block legitimate website content or functionality if it is hosted on domains commonly used by advertisers or if the content's structure (e.g., CSS class names) mimics advertising elements. They do not distinguish between essential and ad-related content in these cases.

What can I do if a website doesn't load because of my ad blocker?

You can try disabling the ad blocker for that specific website, adding the site to your ad blocker's whitelist (allowlist), or trying a different browser without an ad blocker to see if the content loads.

Can websites detect if I am using an ad blocker?

Yes, many websites use scripts that detect the presence of ad blockers. Once detected, they may display a message, restrict access to content, or prevent the page from fully loading to encourage users to disable their ad blockers.

How can website owners prevent ad blockers from breaking their pages?

Website owners should audit their third-party scripts, decouple essential functions from ad-related domains, implement graceful degradation for blocked elements, and consider offering alternative content access instead of aggressive anti-adblock walls.

Why do website pages fail to load or display content with ad blockers? - Technical - Email deliverability - Knowledge base

It can be incredibly frustrating to visit a website only for it to fail to load or display content, especially when you suspect an ad blocker is the culprit. We have all encountered pages that seem to hang, show blank spaces, or even display aggressive messages demanding you disable your ad-blocking software. This phenomenon is becoming increasingly common as websites rely heavily on advertising revenue and intricate tracking scripts to understand user behavior.

The core issue often stems from how ad blockers operate, which isn't always limited to just blocking advertisements. These tools work by identifying and blocking requests to known ad servers, tracking scripts, and other elements that are commonly associated with online advertising. While the intention is to improve user experience by removing intrusive ads and protecting privacy, this blanket approach can sometimes inadvertently break essential website functionality.

Understanding why your ad blocker might be causing a website to malfunction requires a look into the technical interplay between the site's code, the advertising networks it uses, and the filtering rules employed by your ad-blocking extension or software.

How ad blockers work and block content

Ad blockers operate by maintaining extensive blocklists (or blacklists) of URLs, domains, and content patterns associated with advertising, tracking, and known malicious activities. When your browser tries to load a webpage, the ad blocker intercepts the requests and compares them against its blocklist rules. If a request matches a rule, the ad blocker prevents it from loading, effectively removing the unwanted content. This is how ad blockers work at a fundamental level.

The problem arises when website developers tightly integrate critical functions with elements that are also on these blocklists (or blacklists). For example, a website might use a third-party script for analytics that is hosted on a domain also used by an ad network. An ad blocker, seeing the familiar domain, will block the entire script, even if it performs a necessary function for the website to display correctly, such as loading images or interactive forms. This is similar to how email filters can modify or break links in emails if they deem certain elements suspicious.

The filtering process can also be triggered by specific CSS selectors or JavaScript functions that have names or patterns commonly associated with ads. If a developer names a division div.advertisement, an ad blocker might hide it, even if it contains non-ad content. This is why websites can sometimes appear incomplete or broken, not because of a malicious intent, but due to an overzealous blocking rule. Here's an example of a simple ad-blocking filter rule:

Example Ad Blocker Filter Rulesplaintext

||example.com/ads/*
/ads.js
#div.advertisement

Common reasons for broken website functionality

Several factors contribute to website pages failing to load or display correctly when ad blockers are active. One common scenario involves JavaScript files that are crucial for dynamic content or interactive elements. If these scripts are hosted on domains that are on a blacklist (or blocklist), or if their filenames contain keywords that trigger ad blocker rules, they will be prevented from executing, leading to broken functionality. This can manifest as forms not submitting, images not appearing, or entire sections of the page remaining blank. This is similar to how images can intermittently fail to load in email clients.

Another frequent cause is the detection of ad blockers by the website itself. Many sites implement scripts specifically designed to detect if an ad blocker is active. Once detected, the site might display a pop-up message, restrict access to content, or prevent the page from fully rendering. This is done to encourage users to disable their ad blockers or subscribe to a premium service, aiming to recoup lost advertising revenue.

Sometimes, legitimate website resources like fonts, analytics scripts, or content delivery networks (CDNs) can share domains with advertising partners. This tight coupling makes it difficult for ad blockers to differentiate between essential and non-essential content. When a CDN is blocked, for example, it can affect the loading of crucial assets. Similarly, if Google flags your CDN or email content as malicious, it can cause significant deliverability issues.

Ad blockers' intent

Privacy enhancement: Blocking third-party trackers to prevent collection of user data.
Performance improvement: Reducing page load times by preventing large ad files from downloading.
Reduced distraction: Removing intrusive banners, pop-ups, and auto-playing video ads.

Unintended consequences for websites

Content breakage: Essential scripts or content embedded within blocked ad domains fail to load.
Functionality issues: Forms, navigation, or interactive features become unresponsive.
Anti-adblock walls: Websites detect ad blockers and prevent content display entirely.

Impact on user experience and business

The failure of website pages to load or display content due to ad blockers significantly impacts the user experience. Users who rely on these tools for a cleaner, faster browsing experience are often met with broken sites or forced to disable their blockers, which defeats their purpose. This can lead to frustration, a perception of poor website quality, and ultimately, users abandoning the site altogether. It can also lead to issues where tracking links are not working or displaying errors, impacting analytics.

For businesses, this issue can have severe consequences. A broken website can mean lost conversions, reduced engagement, and inaccurate analytics data. If customers cannot access product information, complete purchases, or fill out lead forms, it directly impacts the bottom line. It also creates a negative brand impression, potentially driving users to competitors who offer a smoother browsing experience. Even routine emails with third-party advertisements can get spam blocked, highlighting the pervasive nature of content blocking.

Aspect	Website owners	Users
Revenue	Loss of ad revenue and potential decline in conversions from broken functionality.	Difficulty accessing content or services due to paywalls or blocked elements.
Data accuracy	Skewed analytics due to blocked tracking scripts and incomplete page views.	Concerns over privacy and tracking, reinforcing the use of ad blockers.
Brand reputation	Negative user perception and potential brand damage from a poor experience.	Frustration and abandonment of sites that don't function properly.

Troubleshooting and best practices

If you are a user experiencing issues, the first step is to identify if your ad blocker is indeed the cause. You can try pausing the ad blocker for the specific website or adding the site to your ad blocker's whitelist (allowlist). Most ad blockers provide options to do this directly from their browser extension icon. Restarting your browser or trying a different browser without an ad blocker can also help confirm if it is the root cause, as described by AdBlock's help center. If the site works fine after disabling the ad blocker, you have found your answer.

For website owners, addressing these issues requires a more proactive approach. Regularly auditing your website's scripts and third-party integrations is crucial to identify elements that might be unintentionally blocked. Consider separating critical site functionality from advertising or tracking domains. Where possible, self-host essential scripts or use CDNs that are less likely to be on common blocklists (or blacklists). Implement graceful degradation, ensuring that if a script is blocked, the core content of your site remains accessible. This approach can also improve your overall email domain reputation by association.

When implementing anti-adblock measures, it is important to balance monetization needs with user experience. Instead of an outright content block, consider a polite request to whitelist your site or offer an alternative, ad-free experience for a small fee. Transparency with your users can go a long way in fostering a positive relationship. Also, ensure that all your marketing emails are not blocked, as this can be a more direct communication channel with users.

Tips for website owners

Audit third-party scripts: Regularly check which external scripts are loading and if they are frequently blocked.
Decouple essential functions: Ensure critical website features are not reliant on ad-related domains or frameworks.
Implement graceful degradation: Design your site to function even if some non-critical elements are blocked.
Consider user experience: Avoid aggressive anti-adblock walls that alienate users.

Views from the trenches

Best practices

Regularly test your website with various popular ad blockers to identify potential issues.

Ensure critical site functionalities are served from first-party domains or whitelisted CDNs.

Offer alternative content access for users with ad blockers, such as a reader mode.

Educate your development and marketing teams on how ad blockers impact website rendering.

Common pitfalls

Tightly coupling essential website scripts with third-party ad or tracking domains.

Implementing overly aggressive anti-adblock measures that deter legitimate users.

Using generic naming conventions for CSS classes or JavaScript variables that trigger filters.

Failing to provide a clear explanation or workaround when content is blocked by an ad blocker.

Expert tips

Analyze your web server logs for HTTP requests blocked by client-side tools to pinpoint issues.

Employ a Content Security Policy (CSP) to restrict external resource loading and improve security.

Utilize server-side rendering for critical content to bypass client-side blocking mechanisms.

Segment your audience to understand ad blocker usage and tailor your approach accordingly.

Marketer view

Marketer from Email Geeks says some websites may load correctly in older browsers like Internet Explorer, but not in modern browsers with ad blockers.

March 7, 2019 - Email Geeks

Marketer view

Marketer from Email Geeks says marketing forms, like those from Marketo, often use JavaScript that is frequently blocked by ad blockers.

March 7, 2019 - Email Geeks

Ensuring web content accessibility

The challenge of websites failing to load or display content due to ad blockers is a complex one, balancing user preferences for an ad-free experience with website owners' need for revenue and analytics. As ad blockers become more sophisticated and widely adopted, website developers must adapt their strategies to ensure content accessibility.

By understanding the underlying mechanisms of ad blockers and implementing best practices in website development, it is possible to mitigate these issues. This ensures that content reaches its intended audience, regardless of their browsing preferences, contributing to a healthier and more accessible online environment for everyone. Just like how email authentication standards ensure email deliverability, careful web development ensures content loads as intended.