Summary
While SSL (Secure Sockets Layer) and its successor TLS (Transport Layer Security) primarily focus on data encryption and integrity, their importance extends to email marketing, particularly for tracked links and images. Although a lack of SSL on these assets might not directly cause your emails to land in the spam folder due to a poor sender reputation (as primary email authentication mechanisms like DMARC, SPF, and DKIM are more critical here), it significantly impacts user trust, engagement, and the overall deliverability experience.
Key findings
- User Trust: Emails with insecure links or images (HTTP) can trigger browser warnings or display a broken lock icon, deterring user engagement and eroding trust in your brand.
- Browser Blocking: Modern web browsers, such as Chrome, are increasingly blocking or warning against non-HTTPS content (mixed content) within secure (HTTPS) environments, including emails. This means images might not load, or links might trigger security alerts, negatively affecting the user experience.
- Perceived Security: While SSL on tracked links does not directly impact email deliverability algorithms, the perception of security matters. Users are more likely to trust and click on links that are clearly secure.
- Deliverability Impact (Indirect): If users hesitate to click or if images don't load due to mixed content warnings, it can reduce engagement metrics (e.g., click-through rates). Lower engagement, over time, can indirectly signal to ISPs that your emails are less relevant, potentially affecting your sender reputation.
Key considerations
- User Experience: Ensuring all assets are delivered over HTTPS provides a seamless and secure experience for your recipients, preventing unnecessary warnings and fostering trust.
- Brand Credibility: Using HTTPS for all links and images reinforces your brand's commitment to security and professionalism, which is increasingly expected by consumers.
- Future-Proofing: As browsers and email clients continue to prioritize security, using HTTPS for all email assets is a proactive measure to maintain optimal email performance and avoid potential issues down the line. Elastic Email emphasizes that implementing an SSL certificate can safeguard your tracking domain.
- IP Warming: For new email sending infrastructure or when warming up an IP, eliminating any factor that might negatively impact engagement, such as insecure links, is crucial to building a strong domain reputation quickly.
What email marketers say
Email marketers generally agree that while the direct impact of SSL on tracked links and images on sender reputation and deliverability might not be as pronounced as core email authentication, it's still a critical component for ensuring a positive user experience and avoiding potential roadblocks. Many view it as a necessary cost for maintaining trust and professionalism.
Key opinions
- Good Practice: Even without a direct, measurable impact on deliverability metrics, using HTTPS for all email resources is considered a best practice for overall email health and user perception.
- User Warnings: Non-HTTPS links and images can trigger security warnings in browsers and email clients, which can be a significant deterrent for users clicking on links or viewing content.
- Perception of Sketchiness: A lack of SSL can make emails (and the linked landing pages) appear untrustworthy to recipients, potentially leading to lower engagement and higher spam complaints (even if not directly caused by the lack of SSL).
- Chrome Updates: Upcoming browser updates, such as those from Chrome, were a significant motivator for many marketers to adopt SSL for their email assets, especially for images, to prevent blocking.
Key considerations
- Mandatory for New Implementations: Many marketers consider SSL for all email resources mandatory for any new email marketing platform implementation, especially to support IP warming strategies.
- Align with Web Standards: The internet is moving towards an HTTPS-first standard, and emails should follow suit to align with user expectations and browser behaviors.
- Hidden Costs: Some ESPs charge extra for SSL certificates for custom tracking domains and image hosting, which can be an unexpected cost but is generally deemed worthwhile.
- Click Tracking and Branding: Having secure, branded click tracking links is crucial for conveying credibility and improving the user experience, rather than relying on generic, unsecure links.
Marketer from Email Geeks states that their gut feeling strongly suggests SSL is important for tracked links and images regarding sender reputation and deliverability, even if concrete evidence is hard to pinpoint.
Marketer from Email Geeks explains that they work with Marketing Cloud, which does not secure its links and images by default, requiring an additional SSL certificate purchase to lock them down.
What the experts say
Email deliverability experts generally emphasize the nuanced role of SSL in email. While it is not a direct factor in mailbox provider spam filtering algorithms (unlike DMARC, SPF, and DKIM), it plays a crucial role in the overall user experience and perception of security, which can indirectly influence engagement and, by extension, sender reputation.
Key opinions
- Indirect Reputation Impact: A lack of SSL on tracked links or images doesn't typically lead to direct blocklisting or spam folding by ISPs. However, user interaction issues (like warnings or blocked content) can reduce engagement, which then negatively impacts sender reputation.
- User Trust is Key: Modern internet users are accustomed to seeing HTTPS for secure connections. Emails lacking this can erode trust, leading to fewer clicks and potentially more complaints if users feel unsafe.
- Browser Enforcement: The increasing strictness of web browsers (like Chrome) regarding mixed content (HTTP content on an HTTPS page) means that non-SSL images within emails could simply fail to load, rendering emails incomplete.
- Negative User Signals: Warnings about insecure content, even if not leading to a direct spam folder placement, can contribute to negative user signals (e.g., recipient deletion without opening), which ISPs monitor.
Key considerations
- Holistic Approach: While email authentication (SPF, DKIM, DMARC) is paramount for deliverability, SSL on tracked links and images is part of a holistic approach to building a strong sender identity and ensuring a seamless user experience.
- Preventing Broken Experiences: To prevent broken image displays or jarring browser security warnings upon clicking, all links and images should be served over HTTPS.
- Industry Standard: Email experts agree that serving all content over HTTPS is no longer optional but a fundamental requirement for modern email marketing, as noted by FreshInbox.com regarding Chrome's blocking of non-HTTPS images.
- Consistency Across Channels: Maintaining a consistent secure experience across all digital touchpoints, including email, contributes to overall brand integrity and trust.
Deliverability Engineer from SpamResource.com discusses how mixed content (HTTP assets on an HTTPS page) can lead to unexpected user experiences, emphasizing that while not a direct deliverability factor, it affects how recipients perceive email security.
Expert from Wordtothewise.com states that a key aspect of email authentication is ensuring all components, including tracking domains, are secured with SSL/TLS to align with modern web security practices.
What the documentation says
Official documentation from major email service providers and industry standards bodies strongly recommends the use of HTTPS for all web resources, including those linked within emails. This aligns with a broader internet trend towards ubiquitous encryption to protect user data and ensure content integrity. While explicit rules penalizing HTTP content within emails for deliverability are rare, the emphasis is on providing a secure and consistent user experience.
Key findings
- Security Best Practice: Documentation often frames SSL/TLS as a fundamental security best practice for any content served over the internet, including images and tracked links in emails. This protects data in transit from eavesdropping and tampering.
- Mixed Content Warnings: Browser and email client documentation consistently warns against or describes the blocking of mixed content (HTTP content embedded in an HTTPS page), which is directly relevant to emails with insecure images or tracking links.
- User Experience Focus: The primary concern highlighted in documentation is ensuring a seamless and secure experience for the end-user, free from security warnings or broken content displays.
- Trust Signals: While not directly impacting inbox placement, the absence of SSL can diminish trust signals, which can influence user behavior (e.g., clicks, engagement), a factor indirectly considered by deliverability algorithms.
Key considerations
- Universal Adoption: Most modern email service providers and web platforms now provide SSL for custom domains and assets by default, or as an easily accessible add-on, reflecting its universal importance.
- Protecting Data: SSL encryption is essential for keeping data safe from unauthorized access during transmission, ensuring that click data or image requests cannot be manipulated.
- Compliance and Standards: Adhering to general web security standards by using HTTPS for all assets also contributes to a more compliant and secure email sending infrastructure, which can positively reflect on your overall sender health.
- No Direct Deliverability Penalty (Yet): While there isn't explicit documentation stating HTTP links or images will cause an email to go to spam, the current trend strongly suggests that this could become a direct deliverability factor in the future as internet security measures evolve.
Documentation from Klaviyo Help Center states that email deliverability infrastructure refers to the various systems, tools, and domains used to deliver emails to recipients, implying the holistic nature of factors contributing to deliverability, including security.
CleverReach documentation highlights that SSL encryption is essential for protecting data from unauthorized access during transmission, ensuring third parties cannot manipulate email content or tracking data.
