How do HTTP tracking links affect email deliverability and user experience?
Michael Ko
Co-founder & CEO, Suped
Published 7 Jun 2025
Updated 16 Aug 2025
6 min read
Email marketing relies heavily on tracking to understand campaign performance and user engagement. When I send out emails, I often use tracking links to measure clicks and gather valuable data. However, the protocol used for these tracking links, specifically HTTP versus HTTPS, can significantly impact both email deliverability and the recipient's overall experience.
Using HTTP tracking links, which are unencrypted, poses a considerable risk. While they might seem minor, their presence can trigger spam filters, erode sender reputation, and create a poor user experience for recipients due to security warnings and potential delays. It's crucial to understand these effects to maintain a high level of email marketing effectiveness.
Deliverability impact of HTTP tracking links
HTTP tracking links directly impact email deliverability by raising red flags with mailbox providers and spam filters. These filters are designed to protect users from malicious content, and an unsecured link (HTTP) is often perceived as a potential security threat. This can lead to emails being filtered into spam folders, or even outright blocked, preventing your message from ever reaching the inbox. When it comes to deliverability, every detail matters, including the security of your links.
Many email service providers, especially corporate ones, have stringent security protocols that automatically block or flag emails containing non-HTTPS links. This is a significant concern for B2B senders, but also affects consumer mail because the primary function of a spam filter is to protect its users from security threats. I've observed that unencrypted links can actively contribute to a diminished sender reputation, which is a critical factor in how Google and other providers assess your emails.
The length and quantity of links also play a role. While tracking provides data, excessive use of HTTP links, or very long tracking URLs, can overwhelm email servers and potentially slow down delivery. This can indirectly affect deliverability by signaling suspicious activity. It's important to ensure your tracking links are secure and optimized for performance.
The risk of unsecure HTTP tracking links
Unsecured links in emails can lead to a number of negative outcomes, including decreased inbox placement and an eroded sender reputation. Email clients and security software actively scan for such vulnerabilities.
Spam filters: Mailbox providers may automatically flag emails with HTTP links as suspicious, sending them to junk folders or blocking them entirely.
Reputation damage: Consistent use of unsecure links can negatively impact your sender reputation over time, making it harder to reach the inbox even with future, secure emails.
Blacklists (or blocklists): If your links are associated with malicious activity, your domain could end up on a blacklist or blocklist.
User experience challenges
Beyond deliverability, HTTP tracking links can severely degrade the user experience. When a recipient clicks an HTTP link, modern browsers often display a prominent security warning, indicating that the connection is not secure. This can be alarming for users, leading to distrust and causing them to abandon the click or even mark your email as spam.
Imagine clicking a link only to be greeted by a full-page warning before reaching your intended destination. Most users will click "Go back" rather than navigating through an "Advanced" option to proceed to a potentially unsecured site. This friction creates a poor user journey and wastes the effort you put into crafting your email. It's a direct impedance to engagement and conversions.
Furthermore, the redirection process itself can introduce delays. When a user clicks a tracking link, they are first redirected through a tracking domain before reaching the final destination. If this intermediate tracking link is HTTP, it adds an unnecessary and potentially slow HTTP request. This slight delay, though often milliseconds, can contribute to a frustrating user experience, especially on slower connections. Ensuring link redirects are seamless is critical for user satisfaction.
Security implications
The security aspect of HTTP tracking links cannot be overstated. Unlike HTTPS, HTTP connections are not encrypted. This means that data sent between the user's browser and the tracking server can be intercepted by third parties, making it vulnerable to man-in-the-middle attacks. While the tracking data itself might not be sensitive, an unencrypted connection to your tracking domain can still be exploited.
An attacker could potentially inject malicious code into the unencrypted traffic, which could then be delivered to the user's machine. This risk exists even if the final destination URL is secure. Mailbox providers like Microsoft Defender for Office 365 are specifically designed to protect users from malicious links, highlighting the severity of unsecured connections.
I've always advocated for a secure online environment, and this extends to email links. While the risk might vary depending on the content of the linked page, the principle remains: unsecured communication paths are a vulnerability. Ensuring all engagement tracking uses HTTPS is a fundamental step in protecting both your recipients and your sender reputation.
Deliverability risk: Higher chance of landing in spam or being blocked.
User friction: Recipients may abandon clicks due to perceived insecurity.
Reputation damage: Damages sender reputation over time.
HTTPS tracking links
No warnings: Smooth user experience without security prompts.
Improved deliverability: Enhances trust with mailbox providers and spam filters.
Higher engagement: Encourages clicks and positive user interaction.
Protects reputation: Maintains a healthy sender reputation.
Best practices for tracking links
To ensure your email marketing efforts are successful, it's paramount to use HTTPS for all tracking links. Most reputable email service providers (ESPs) offer SSL (Secure Sockets Layer) for link tracking as a standard feature. If your links are still resolving as HTTP, it's crucial to work with your vendor to identify and correct the issue, as was the case for a client I recently assisted.
Implementing a custom tracking domain with SSL enabled is another best practice. This allows your tracking links to appear branded and secure, reinforcing trust with your recipients and mailbox providers. For example, instead of a generic tracking URL, you can have clicks.yourdomain.com over HTTPS. This also helps with subdomain alignment, further boosting deliverability.
If you cannot immediately switch to HTTPS for tracking links, consider alternative strategies or temporarily disable tracking if the user experience and deliverability risks are too high. For specific links, some platforms allow you to exclude them from tracking. For instance, SendGrid provides an attribute to disable click tracking for individual HTML links.
Final thoughts on secure tracking
In the complex world of email deliverability, seemingly minor technical details can have a ripple effect on your entire email program. HTTP tracking links, while offering data, introduce significant risks to both your inbox placement and your recipients' trust.
Prioritizing secure, HTTPS-enabled tracking links is not just a best practice, it's a necessity for modern email marketing. It protects your sender reputation, ensures your messages reach the intended inbox, and provides a smooth, secure experience for your subscribers, ultimately leading to better engagement and campaign performance.
Views from the trenches
Best practices
Always use HTTPS for all tracking links to enhance security and improve recipient trust.
Configure a custom tracking domain with SSL enabled to brand your links and improve domain alignment.
Regularly monitor your email deliverability rates to catch any issues related to link security or spam filtering.
Work closely with your email service provider to ensure all tracking mechanisms are properly secured and configured.
Educate your team on the importance of secure links to avoid accidental use of HTTP in email content.
Common pitfalls
Ignoring browser security warnings on HTTP links can lead to low click-through rates and high bounce rates.
Failing to update legacy email templates that may still contain insecure HTTP tracking URLs.
Assuming that if the final landing page is HTTPS, the tracking link doesn't need to be, which is incorrect.
Using generic, non-branded tracking domains that can raise suspicion with spam filters and recipients.
Not understanding that insecure links can contribute to your domain being put on an email blocklist.
Expert tips
Consider disabling click tracking for highly sensitive emails (like password resets) if you can't guarantee HTTPS.
Implement DMARC policies to further protect your domain from impersonation and spoofing, which complements link security.
Regularly test your email campaigns using an email deliverability tester to verify link functionality and security.
For transactional emails, ensure any automated tracking links are correctly configured for HTTPS from the start.
Audit third-party integrations that add tracking links to ensure they adhere to secure protocols.
Marketer view
Marketer from Email Geeks says that there is a very good chance subscribers are seeing a message about an unsecure link, which will show them a browser page warning, and they will likely click 'Go back' instead of 'Advanced' to proceed.
2023-04-10 - Email Geeks
Expert view
Expert from Email Geeks says that mailbox providers definitely block content with non-HTTPS links, which is more typical for B2B senders and corporate spam filters, but it is also a concern for consumer mail.
Microsoft Defender for Office 365 are specifically designed to protect users from malicious links, highlighting the severity of unsecured connections.
