Do HTTP tracking links affect email deliverability?
Matthew Whittaker
Co-founder & CTO, Suped
Published 26 Jul 2025
Updated 19 Aug 2025
6 min read
Email tracking links are essential tools for marketers and businesses, providing valuable insights into how recipients interact with their campaigns. These links, often managed by your email service provider (ESP), redirect clicks through a tracking domain before sending the user to the final destination. Traditionally, many of these tracking links were configured using HTTP, but with the widespread adoption of HTTPS for web security, a question arises: Do HTTP tracking links affect email deliverability?
The short answer is yes, they can, and increasingly so. Modern email systems and user expectations heavily favor secure connections. Using HTTP links, even for redirects, introduces potential vulnerabilities and can raise red flags with spam filters and inbox providers, ultimately impacting whether your emails reach the inbox or land in the spam folder.
The http versus https distinction
The primary difference between HTTP and HTTPS lies in security. HTTPS (Hypertext Transfer Protocol Secure) encrypts data transmitted between a user's browser and a website, protecting against eavesdropping and tampering. HTTP (Hypertext Transfer Protocol), on the other hand, transmits data in plain text, making it vulnerable to interception.
When an email contains an HTTP tracking link that redirects to an HTTPS website, it creates a momentary insecure connection. While the final destination is secure, this initial insecure hop can be a concern. Email clients and security software are becoming more stringent in flagging or penalizing any links that initiate with HTTP, even if they quickly redirect. This behavior is considered an SSL issue by some providers.
Many email service providers (ESPs) historically defaulted to HTTP tracking links because it required less technical overhead, particularly concerning SSL certificate management for custom tracking domains. However, as the internet moves towards ubiquitous encryption, this practice is quickly becoming outdated and can cause deliverability challenges.
Impact on sender reputation and spam filters
Email deliverability heavily relies on your sender reputation, a score assigned by Internet Service Providers (ISPs) and email clients based on your sending practices. Using HTTP tracking links can negatively impact this reputation. Spam filters are constantly evolving to identify and block (or blacklist) suspicious content, and unencrypted links are often seen as a potential threat vector for phishing or malware.
Even if your final destination is HTTPS, the initial HTTP tracking link can trigger spam filters, leading to your emails being diverted to the spam folder or outright rejected. Some sources indicate that email tracking links are mostly blacklisted by ESPs if not properly configured or if they exhibit suspicious behavior, such as a protocol mismatch.
HTTP tracking
Security risk: Data transmitted in plain text, susceptible to interception.
Spam filters: Higher likelihood of triggering spam filters or blocklists due to perceived insecurity.
User trust: Can display browser warnings or appear less trustworthy.
Branding: Often associated with generic or shared tracking domains, reducing brand consistency.
HTTPS tracking
Security: Encrypted data transmission, enhancing security and privacy.
Spam filters: Improves sender reputation and reduces chances of being flagged by filters.
User trust: Builds confidence and trust with recipients, as links appear secure.
Branding: Allows for custom, branded tracking domains over HTTPS.
Many ISPs, including Gmail, prefer and even implicitly reward the use of HTTPS for all elements within an email. The presence of HTTP links, especially those for tracking, can contribute to a lower spam score and potentially lead to messages being filtered into junk folders.
User experience and brand perception
Beyond the technical aspects of deliverability, HTTP tracking links can significantly erode recipient trust and negatively affect the user experience. When users click on a link, they expect a seamless and secure transition to the destination. Seeing an http:// prefix, or worse, a browser warning about an insecure connection, can immediately trigger suspicion. This perception of insecurity can lead to abandoned clicks, reduced engagement, and even unsubscribes.
A key aspect of building and maintaining a strong sender reputation is consistency and professionalism. A mismatch between the tracking link protocol and your brand's website protocol (e.g., HTTP tracking redirecting to HTTPS site) can look unprofessional and raise concerns about phishing attempts or a lack of attention to security. This discrepancy can impact deliverability.
Best practices for link security
To ensure optimal deliverability and user experience, always strive to use HTTPS for all links within your emails, including tracking links. This alignment builds trust with both recipients and email providers. Implementing SSL for your custom tracking domain is crucial.
A poorly perceived link can lead to reduced click-through rates, even if your email content is compelling. This lack of engagement, in turn, can signal to ISPs that your emails are not valuable, further harming your sender reputation and leading to future deliverability issues. It's a cyclical effect where perceived insecurity directly impacts your email program's performance.
Practical implications and solutions
Transitioning from HTTP to HTTPS tracking links often involves technical work on the ESP's side, as it requires obtaining and managing SSL certificates for tracking domains. Some ESPs may charge additional fees for this service, citing the effort involved in setting up and maintaining these certificates. However, the investment is usually worthwhile given the deliverability and trust benefits.
It's important to advocate for custom branded tracking links over HTTPS. This means the tracking domain should align with your sending domain, rather than using a generic ESP-shared domain. This practice significantly boosts recipient trust and helps maintain a cohesive brand identity throughout the email journey, strengthening your domain alignment. Even if the ESP charges for it, it's a critical component for modern email sending.
While it can be challenging to influence an ESP's default configurations, pushing for HTTPS tracking links on your custom domain is a non-negotiable step for long-term deliverability success. It contributes to a stronger sender reputation and ensures a more secure and professional experience for your recipients.
Views from the trenches
Best practices
Always push your ESP to support HTTPS for custom tracking domains.
Ensure your tracking domain is a custom branded domain, not a shared ESP domain.
Prioritize securing SSL certificates for all tracking links to enhance trust.
Common pitfalls
Accepting HTTP tracking links as a 'preference' rather than a deliverability requirement.
Not pushing for custom branded tracking links, settling for shared domains.
Failing to renew SSL certificates for tracking domains, causing service disruption.
Expert tips
Consider the end-user experience, as a random, unbranded, or insecure link can cause mistrust and lost conversions.
While obtaining SSL certificates for custom tracking domains can involve effort and cost, it is a crucial investment in modern email sending.
It's generally better for deliverability to have an HTTP link with your own branded domain than an HTTPS link with a shared ESP domain, though HTTPS with your own domain is ideal.
Marketer view
A marketer from Email Geeks says they would definitely push back on their ESP to get their TLS security in order because HTTP tracking links are suspicious behavior.
2019-08-05 - Email Geeks
Marketer view
A marketer from Email Geeks says that if a tracking link gets blacklisted, it could definitely cause deliverability problems, so prioritizing HTTPS is important.
2019-08-05 - Email Geeks
Ensuring secure engagement tracking
HTTP tracking links can indeed affect email deliverability by negatively influencing sender reputation, increasing the likelihood of emails being flagged by spam filters or ending up on a blocklist (or blacklist), and eroding recipient trust. In today's security-conscious digital landscape, where HTTPS is the standard for web traffic, using HTTP for any part of your email's user journey is a step backward that can carry tangible penalties.
For optimal email deliverability, prioritize implementing HTTPS for all tracking links, ideally on a custom branded domain. While there might be technical or financial hurdles involved with your ESP, the long-term benefits of improved inbox placement and enhanced brand trust make it a worthwhile investment. Ensuring secure, consistent, and trustworthy links is a fundamental component of a successful email program.
Gmail, prefer and even implicitly reward the use of HTTPS for all elements within an email. The presence of HTTP links, especially those for tracking, can contribute to a lower spam score and potentially lead to messages being filtered into junk folders.
