Is SSL important for tracked links and images in email marketing sender reputation and deliverability?
Matthew Whittaker
Co-founder & CTO, Suped
Published 2 Jul 2025
Updated 15 Aug 2025
7 min read
When crafting email marketing campaigns, we often focus on compelling content, strong calls to action, and effective audience segmentation. However, the underlying technical infrastructure, particularly around security protocols like SSL (Secure Sockets Layer), plays a crucial role that is sometimes overlooked. The question of whether SSL is important for tracked links and images in email marketing is not just about security, but also fundamentally impacts sender reputation and deliverability. It is a critical component for maintaining trust and ensuring your messages reach the inbox.
In today's digital landscape, users and mailbox providers (like Google and Microsoft) are increasingly prioritizing secure web experiences. This extends beyond just your website to every element within your emails, including tracking pixels, linked images, and URL redirects. An email campaign that features non-secure (HTTP) content can undermine recipient confidence and raise red flags with spam filters.
Navigating the complexities of email deliverability requires attention to detail, and securing all outbound links and hosted images with SSL is a fundamental step. It contributes to a positive user experience, strengthens your brand's credibility, and is widely considered a best practice in modern email marketing. Let's delve into why this often-overlooked aspect is so vital for your campaigns.
The foundational role of SSL/TLS in email security
SSL/TLS (Transport Layer Security, the successor to SSL) certificates encrypt data exchanged between a user's browser or email client and a server. For email marketing, this means that when a recipient clicks a tracked link or views an image hosted on an external server, the connection is secure. This encryption protects data from being intercepted or tampered with by malicious actors, safeguarding both sender and recipient.
The absence of SSL on tracked links or images creates mixed content issues. This occurs when a secure page (like an email opened in a modern webmail client) attempts to load insecure resources (HTTP images or links). Browsers and email clients are designed to flag or block such content to protect users. For example, Google Chrome has taken steps to block non-HTTPS images in emails, which can lead to broken image icons, disrupting the visual integrity of your campaigns.
Avoiding mixed content warnings
Mixed content can trigger security warnings for recipients, such as a not secure padlock icon with a line through it, or a general security warning. This can significantly erode trust and make your emails appear suspicious, even if they are legitimate marketing messages.
Ensure all resources loaded within your emails, including images and tracking pixels, use HTTPS to prevent these warnings and maintain a consistent, secure experience for your subscribers.
Implementing SSL on all email assets is a critical step towards maintaining high standards of email security. Beyond protecting user data, it reinforces your brand's commitment to security and professionalism. This fundamental layer of protection helps prevent vulnerabilities that could be exploited by phishers or spammers, further solidifying your sender identity.
Impact on sender reputation and deliverability
While an HTTP link might not directly land your email in the spam folder, its indirect impact on sender reputation and email deliverability is significant. Mailbox providers, such as Yahoo, consider non-SSL references spammy, which can lower your sending reputation score. They continuously evaluate various signals to determine if an email is legitimate, and the use of secure protocols is one such signal.
A negative user experience, triggered by security warnings or broken images due to insecure content, directly influences engagement metrics. If recipients hesitate to click links or report your emails as spam because of perceived security risks, your domain reputation will suffer. This decline in reputation can lead to lower inbox placement rates, higher bounce rates, and even placement on a blocklist (or blacklist).
While the core algorithms that determine whether an email goes to the inbox or spam folder might not immediately penalize HTTP links with a direct block, the cumulative effect of negative user interaction can be profound. Mailbox providers prioritize the safety and experience of their users. An email that appears untrustworthy, even subtly, will be treated with suspicion, regardless of its content or sender. This includes potential issues with visible link domain mismatches or HTTP/HTTPS protocol discrepancies, which can both raise red flags.
HTTP tracking and deliverability
User Warnings: Triggers security warnings in browsers or email clients, discouraging clicks.
Broken Content: Images might not load, impacting email design and professionalism.
Reputation Impact: Indirectly harms sender reputation due to poor user engagement and perceived insecurity.
Brand Trust: Erodes recipient trust, making future emails less likely to be opened.
HTTPS tracking and deliverability
Enhanced Trust: Displays a secure padlock, building confidence in your brand.
Improved Experience: All content loads correctly, ensuring your email design is seen as intended.
Positive Signals: Contributes to a positive sender reputation and better inbox placement.
Data Security: Encrypts user data during interactions, enhancing privacy.
Practical considerations for email marketers
Most email marketing platforms (ESPs) use custom tracking domains for links and sometimes for images to monitor engagement metrics such as opens and clicks. These tracking domains are usually subdomains of your main sending domain (e.g., links.yourdomain.com or img.yourdomain.com). It is absolutely vital that these specific subdomains also have an SSL certificate configured and are serving content over HTTPS. If your ESP does not offer this by default, or requires an additional purchase, it is a worthwhile investment. Not securing these can also lead to deliverability issues for HTTP tracking links.
Beyond the technical security aspects, using HTTPS for all elements within your email demonstrates a commitment to user privacy and modern web standards. This attention to detail can subtly reinforce your brand's professionalism and trustworthiness. In an era where cybersecurity threats are prevalent, anything you can do to signal a secure environment is beneficial. This is closely related to why it's also important to ensure outbound TLS is configured for email marketing, securing the entire email transmission path.
Example of an email snippet with secure links and imagesHTML
The consistency of using secure links and images across all your email communications contributes to a cleaner, more professional presentation that builds recipient confidence. Many email marketers are seeking to improve their email deliverability by addressing every possible factor that influences sender reputation. Securing tracked links and images with SSL is a fundamental part of this comprehensive approach, ensuring your emails are perceived as trustworthy and professional by both recipients and mailbox providers.
Views from the trenches
Best practices
Always ensure all tracked links and images in your emails use HTTPS to maintain a consistent, secure experience for recipients.
Verify that your email service provider offers SSL for custom tracking domains and activate it to prevent mixed content warnings.
Educate your marketing team on the importance of SSL for all email assets to support overall deliverability and brand trust.
Regularly check your email previews across various clients and browsers to confirm all links and images render securely.
Common pitfalls
Relying on default ESP settings that might not include SSL for tracked links or images, leading to insecure content.
Underestimating the negative impact of browser security warnings on recipient engagement and overall sender reputation.
Failing to renew SSL certificates for tracking domains, causing temporary but significant disruptions to link and image loading.
Ignoring browser updates (like Chrome blocking non-HTTPS images) that can suddenly break email content for many recipients.
Expert tips
Consider a dedicated IP and domain if you send high volumes, enabling full control over your sending reputation, including SSL configuration.
Use email deliverability testing tools to check for broken links or insecure content before sending campaigns to your audience.
Align your tracking domain with your sending domain to further enhance trust signals for mailbox providers.
Monitor user engagement metrics closely, as dips in open or click rates could be an early indicator of trust issues related to insecure content.
Marketer view
Marketer from Email Geeks says they were not personally aware of any direct reputation impact, but considers using HTTPS for all resources a good practice, even if it comes at an added cost.
2020-09-16 - Email Geeks
Marketer view
Marketer from Email Geeks says that while non-HTTPS links may not cause mail to go to the bulk folder, they can trigger warnings for users when clicked, which is a bad idea overall.
2020-09-17 - Email Geeks
Maintaining trust and maximizing inbox placement
In the complex ecosystem of email marketing, every detail contributes to your overall success. While the direct link between SSL on tracked assets and immediate deliverability to the inbox might seem subtle, its cumulative impact on sender reputation and recipient trust is undeniable. Ignoring the importance of HTTPS for all your email elements, from links to images, means risking user experience and potentially undermining your hard-earned domain reputation (or brand reputation).
Modern email clients and webmail interfaces are increasingly vigilant about security. They want to ensure that every part of an email provides a safe browsing experience. By consistently employing SSL, you're not only encrypting data but also signaling to mailbox providers that you are a legitimate and trustworthy sender. This proactive approach helps to avoid mixed content warnings, ensures your email designs render correctly, and, crucially, fosters recipient confidence. Ultimately, this leads to better engagement and improved inbox placement.
Prioritizing SSL for all tracked links and images is not just a technical formality, but a strategic decision that directly supports your email marketing goals. It reinforces your sender reputation, enhances deliverability, and protects the integrity of your brand in every message you send. Embracing these security best practices is essential for sustained success in today's digital communication landscape.
Google and 
Microsoft) are increasingly prioritizing secure web experiences. This extends beyond just your website to every element within your emails, including tracking pixels, linked images, and URL redirects. An email campaign that features non-secure (HTTP) content can undermine recipient confidence and raise red flags with spam filters.
Yahoo, consider non-SSL references spammy, which can lower your sending reputation score. They continuously evaluate various signals to determine if an email is legitimate, and the use of secure protocols is one such signal.
