Why do spam filters care about HTTP vs. HTTPS links?

Spam filters prioritize user security. HTTP links are unencrypted and vulnerable to interception, making them suspicious. Even if they redirect to HTTPS, the initial insecure connection can trigger a flag, contributing to a higher spam score.

Will an HTTP link that redirects to HTTPS still be penalized?

Yes, potentially. While the final destination is secure, the initial HTTP connection can still raise red flags for spam filters and modern browsers. This "mixed content" scenario can negatively impact how your email is perceived.

Are link shorteners always bad for email deliverability?

Not always, but they can be. Link shorteners are frequently used by spammers to hide malicious URLs, leading spam filters to view them with suspicion. If you must use them, ensure they resolve to a reputable, HTTPS-secured domain and use them sparingly.

How can I check if my links are affecting my email deliverability?

Beyond monitoring your overall deliverability metrics, you can use email testing tools to analyze your email content for potential spam triggers, including problematic links. Pay close attention to any warnings related to insecure links.

What is the easiest way to ensure all my email links are HTTPS?

Ensure your website and all landing pages are fully secured with HTTPS. When creating emails, manually verify that all URLs (including images and tracking links) start with https:// . Most modern Email Service Providers (ESPs) automatically handle tracking links with HTTPS, but it's always good to confirm.

Are HTTP links penalized by spam filters in email marketing? - Sender reputation - Email deliverability - Knowledge base

The question of whether HTTP links are penalized by spam filters in email marketing is one that often arises. Many marketers are told that including HTTP URLs, even those that redirect to HTTPS, can lead to deliverability issues. This concern stems from the evolving landscape of email security, where trust and authenticity are paramount for mailbox providers.

While it might seem like a minor detail, the protocol used in your links can indeed play a role in how your emails are scored by spam filters. Understanding this nuance is crucial for maintaining a strong sender reputation and ensuring your messages reach the intended inboxes.

The internet's move to secure connections

In recent years, there has been a significant industry-wide push towards Hypertext Transfer Protocol Secure (HTTPS) as the standard for web communication. This shift is driven by the need for enhanced data security and user privacy. Major browsers and search engines actively encourage, and sometimes enforce, the use of HTTPS, signaling a clear preference for secure connections.

This preference extends to how links are evaluated within email ecosystems. Even if an HTTP link ultimately redirects to an HTTPS destination, the initial non-secure protocol can be viewed with suspicion. This is because the redirect process introduces an additional step where data could potentially be intercepted or tampered with before the secure connection is established. It's about the perceived security at the point of click.

The general consensus among email professionals is that adhering to the most secure practices, including using HTTPS for all links, is a foundational element for optimal email deliverability. This aligns with broader internet trends and the expectations of modern email clients and spam filters. Some sources even indicate that Gmail began flagging non-HTTPS links as early as 2019. Further discussion on mixed content and mixed messages also highlights this issue.

How spam filters scrutinize email links

Spam filters employ complex algorithms to analyze various elements of an email, including its links, to determine its legitimacy. They look for patterns and indicators that are commonly associated with malicious or unsolicited bulk email (spam). Every link within your email, whether it's an HTTP or HTTPS link, undergoes this rigorous examination.

One key factor is the reputation of the linked domain. If your email contains a link to a domain with a poor reputation or one that appears on a common blocklist (or blacklist), it can significantly harm your email's deliverability. Filters also scrutinize the number and type of links, flagging emails that appear overly "linky" or use tactics like unencoded URLs, which can be seen as suspicious.

Link shorteners, for instance, are often associated with spam because they can obscure the final destination of a link, making it harder for both users and filters to assess trustworthiness. While not inherently bad, their use requires careful consideration to avoid triggering spam filters. You can learn more about whether link shorteners are bad for email marketing in a related article. Moreover, spam filters may even follow links to scan the content of the destination page. If the landing page hosts malware, phishing content, or looks suspicious, the email originating the link will be penalized.

Direct impact of HTTP links on deliverability

While there might not always be a direct, stated policy from every mailbox provider explicitly penalizing HTTP links, their presence can indirectly but significantly impact deliverability. An initial HTTP link in an email, even if it redirects, raises a flag for many spam filters because it indicates a less secure connection. This can contribute to a higher spam score for your email.

Mailbox providers, like Google, are increasingly prioritizing security across all their services, including Gmail. Their stated policies for web search often influence their email filtering logic. For example, if Google Search penalizes non-HTTPS pages, it stands to reason that Gmail's spam filters would also be wary of such links in emails. This aligns with the concept of mixed content, where secure pages load insecure resources, which can be an issue in webmail clients as well.

The risk isn't just about direct penalties. User experience also plays a role. If a recipient clicks an HTTP link and their browser or email client warns them about an insecure connection, it erodes trust. This can lead to lower engagement, more spam complaints, and a damaged sender reputation, ultimately affecting future email campaigns. This concern is amplified when considering tracking links used by Email Service Providers (ESPs). Some ESPs might still use HTTP for their tracking redirects. While this might be done for "compatibility," it presents a potential vulnerability that more security-conscious mail systems could flag, potentially leading to "cannot connect securely" errors in browsers like

Safari. As a best practice, always ensure your entire link chain, including redirects and tracking links, uses HTTPS.

Risk of HTTP links

Insecure connections: HTTP links do not encrypt data, making them vulnerable to interception.
Browser warnings: Modern browsers (e.g., Chrome) often flag HTTP sites as "not secure," deterring users.
Spam filter scrutiny: Filters are more likely to flag emails with HTTP links as suspicious due to security concerns.
Reputation damage: Consistent use of HTTP links can negatively impact your domain reputation.

Implementing best practices for secure linking

To maximize your email deliverability, the simplest and most effective strategy is to exclusively use HTTPS for all links within your emails. This includes links to your website, landing pages, images, and any tracking URLs. Ensuring every link begins with https:// signals trustworthiness to both spam filters and recipients. You can also review how HTTP links affect email deliverability for more detailed information.

Beyond just the protocol, the quality and context of your links are equally important. Avoid using excessive links that appear suspicious or out of place. Ensure your link text is clear and accurately describes the destination. For example, instead of linking to https://www.example.com/long-url-with-parameters, use descriptive anchor text like "Visit our website" or "Read the full article." Understanding how hyperlinks in the body affect deliverability can further optimize your strategy.

Regularly monitor your domain's reputation. If your domain or any domains you link to are listed on a blocklist (or blacklist), it will severely affect your email deliverability, regardless of whether your links are HTTP or HTTPS. Tools that help with blocklist monitoring can be invaluable. Additionally, strong email authentication protocols, such as DMARC, SPF, and DKIM, are essential for verifying your sender identity and reducing the likelihood of your emails being flagged as spam.

Views from the trenches

Best practices

Always use HTTPS for all links within emails, including images and tracking URLs.

Obtain free SSL certificates from providers like Let's Encrypt to secure your domains.

Ensure your email service provider's tracking links also use HTTPS to avoid security warnings.

Common pitfalls

Relying on HTTP links even if they redirect to HTTPS, as initial connections can still be flagged.

Overlooking the indirect impact of HTTP links on sender reputation and user trust.

Assuming an email service provider's use of HTTP tracking for 'compatibility' is sufficient for deliverability.

Expert tips

Regularly audit your email content for any remaining HTTP links.

Monitor your email deliverability metrics closely after switching to HTTPS links.

Educate your team on the importance of HTTPS for all digital assets, not just emails.

Marketer view

Marketer from Email Geeks says they have seen a non-zero shift in delivery for HTTP versus HTTPS and now recommend all clients move to HTTPS going forward.

2024-09-24 - Email Geeks

Marketer view

Marketer from Email Geeks says that at this point, SSL certificates can be free via Let'sEncrypt, and while there might be a few technical reasons not to use HTTPS, these are generally overcome with better technical solutions.

2024-09-24 - Email Geeks

Key takeaways for deliverability

The short answer to whether HTTP links are penalized by spam filters is nuanced, but the clear guidance is to avoid them. While not every filter will directly "penalize" an HTTP link with a hard block, the indirect consequences, such as increased scrutiny, negative reputation impact, and poor user experience, make them a significant risk. The internet has moved towards a secure-by-default standard, and email marketing must follow suit.

By consistently using HTTPS for all your email links, you align with modern security standards, build trust with mailbox providers and recipients, and significantly improve your chances of landing in the inbox. Prioritizing secure connections is an investment in your email deliverability and overall brand reputation.