What is the purpose of confusing HTML links in spam emails?
Matthew Whittaker
Co-founder & CTO, Suped
Published 9 May 2025
Updated 17 Aug 2025
7 min read
When sifting through an inbox, especially after some time away, it is common to encounter spam emails. These often feature HTML links that look strange or confusing. I have seen many instances of heavily obfuscated or misleading links, which raises the question: Why do spammers go to such lengths to make their links confusing?
The primary goal is twofold: to bypass spam filters and to trick recipients into clicking. These seemingly jumbled links are not accidental, they are carefully crafted to evade detection by automated systems while still appearing just plausible enough to a human eye. It is a constant game of cat and mouse between spammers and email security professionals, where every trick is analyzed and countermeasures are developed.
Understanding these tactics is crucial for protecting yourself and your organization from potential threats. It also provides insight into the challenges involved in maintaining high email deliverability, as legitimate senders must also navigate the complexities of email systems without triggering false positives from spam filters.
Deceptive tactics and obfuscation techniques
Spammers employ various deceptive techniques to make HTML links confusing. One common method involves using hidden characters within the URL or the display text itself. These characters are often invisible to the human eye but can disrupt the parsing capabilities of less sophisticated spam filters.Hackers evade email spam filters by inserting hidden text.
Another tactic is URL obfuscation, where the true destination of the link is obscured using encoding, multiple redirects, or by embedding the malicious URL within a seemingly benign one. For example, a link might appear to go to a trusted domain, but the actual phishing link itself is hidden or the entire script is obfuscated. These methods are designed to make it difficult for both automated systems and users to discern the actual destination.
Sometimes, spammers use attributes like target="_blank" in conjunction with misleading display text. While target="_blank" simply opens a link in a new tab, in a spam context, it can add to the disorientation, making it harder for recipients to track where they are being sent. The primary purpose of these confusing links is often just to trick humans, and sometimes even less advanced spam filters, that do not fully interpret HTML.
Evading spam filters and blocklists
Confusing HTML links are a direct response to the sophistication of modern spam filters. These filters analyze email content, including links, for patterns associated with malicious or unsolicited mail. By using various obfuscation techniques, spammers try to make their links look benign to automated systems, thus avoiding being flagged as spam or getting their sending domains added to a blocklist (or blacklist). If a domain is blocklisted, its emails are likely to be rejected or sent straight to the junk folder.
Spammer goals
Bypass filters: Avoid detection by spam filters that scan for known malicious URLs or suspicious link patterns.
Deceive users: Present a link that appears legitimate or intriguing to trick recipients into clicking it.
Evade reputation checks: Prevent the true malicious domain from being quickly identified and added to blocklists.
Legitimate sender goals
Clear communication: Ensure links are easily understandable and lead directly to the intended content.
Maintain trust: Build and preserve sender reputation by avoiding any spam-like characteristics.
Optimize deliverability: Structure emails to pass through spam filters without being flagged.
Advanced email security solutions, such as Safe Links, are designed to combat these deceptive tactics. These systems actively check links at the time of arrival and at the time of click, providing an additional layer of protection against newly compromised sites or zero-day phishing attacks. However, spammers continue to innovate, constantly seeking new ways to exploit vulnerabilities in filters and human judgment.
Psychological manipulation of recipients
Beyond technical evasion, confusing HTML links are powerful tools for psychological manipulation. Spammers often create emails that look like they come from legitimate sources, such as major brands or service providers. The confusing link might then be presented in a way that blends in with the rest of the email's design or appears as a call to action.
For instance, a link might show a well-known domain name like Amazon or university webmail, while the underlying actual link is hidden and leads to a malicious site. This visual trickery is designed to instill a false sense of security, encouraging users to click without careful inspection. It's why I always recommend hovering over links to check their destination before clicking.
The urgency often conveyed in spam and phishing emails also plays a role. Messages that demand immediate action, like "Your account will be suspended!" or "Click here for a special offer!", are crafted to bypass rational thought. When combined with a confusing HTML link, the recipient is less likely to scrutinize the link's legitimacy, making them more susceptible to social engineering attacks.
Impact on email deliverability
For legitimate email marketers, understanding these spam tactics is vital because how hyperlinks in the body of an email affect deliverability is significant. Even well-intentioned emails can face deliverability issues if their HTML structure or link practices resemble those of spammers. Too many links, improperly formatted HTML, or even tracking links that get misidentified can lead to emails being flagged.
Spam filters are constantly learning and evolving. If your email contains elements that are commonly associated with spam, like highly obscured links or malformed HTML, it can negatively impact your sender reputation. This can lead to your emails being directed to the spam folder, even if your content is legitimate. I always stress the importance of clean, well-structured HTML and transparent linking practices.Malformed HTML impacts deliverability and spam filtering.
Ensuring proper email authentication, such as DMARC, SPF, and DKIM, is another critical step. These protocols help email providers verify that incoming mail is indeed from the stated sender, reducing the effectiveness of spoofing attempts that often accompany confusing links. This is especially important for transactional and marketing emails that rely heavily on links for user engagement.
The ongoing battle
From a deliverability standpoint, a common issue is that hidden links in emails get high click rates from bots and automated systems. These aren't human clicks, but automated scans by security filters that can distort your engagement metrics. Therefore, it is important to avoid false email click and open data from anti-spam bots. Being aware of these automated interactions helps in accurately assessing campaign performance and maintaining a healthy sender reputation.
Confusing HTML links in spam emails are a deliberate tactic. They aim to exploit weaknesses in spam filters and the vigilance of human recipients. While these tactics pose a significant challenge, ongoing advancements in email security and increased user awareness are critical in combating them. For senders, maintaining strong authentication, clean HTML, and transparent linking practices is paramount to ensuring messages reach their intended audience, rather than the spam folder.
Views from the trenches
Best practices
Always inspect the full URL by hovering over links before clicking, especially in suspicious emails.
Use email security solutions that offer 'Safe Links' or similar link-scanning features.
Educate your team about common phishing and spam techniques, including confusing links.
Common pitfalls
Assuming a link is safe because the display text looks legitimate without verifying the actual URL.
Clicking on links in emails that create a sense of urgency or unexpected offers.
Ignoring browser warnings about malicious or untrusted websites after clicking a link.
Expert tips
Implement DMARC with a strong policy to protect your domain from being used in spoofing attacks that often contain confusing links.
Regularly monitor your email deliverability metrics for unusual spikes in link clicks, which could indicate bot activity.
Maintain minimal and clean HTML in emails to reduce the chances of legitimate emails being confused for spam.
Expert view
Expert from Email Geeks says confusing HTML links are often designed to bypass rudimentary spam filters and primarily to deceive human recipients who might not inspect the underlying code, despite a target attribute that suggests some spamware is vague on its HTML usage.
2023-01-02 - Email Geeks
Marketer view
Marketer from Email Geeks says they often encounter email links that are so convoluted they struggle to understand their function from an HTML perspective.
