Does using Google Fonts preconnect links in emails negatively affect SpamAssassin reputation?
Matthew Whittaker
Co-founder & CTO, Suped
Published 14 Jun 2025
Updated 17 Aug 2025
6 min read
The question of whether using Google Fonts preconnect links in emails negatively affects SpamAssassin reputation is a common one, especially when you encounter specific feedback like a manager suggesting it. I recently heard of a similar situation where a manager insisted on removing these links from email templates, citing a SpamAssassin warning that the domains were empty/broken.
This kind of feedback can be confusing, particularly since preconnect tags are standard practice for optimizing web content that uses Google Fonts. We need to dissect this claim and understand how email systems, especially spam filters like SpamAssassin, truly evaluate links and external resources.
The role of SpamAssassin in email filtering
SpamAssassin is an open-source spam filter, and it works by assigning scores to various elements within an email. If the total score exceeds a certain threshold, the email is flagged as spam. While it's a well-known tool, it's important to understand its place in the modern email ecosystem.
Major email service providers, such as Google and Microsoft, primarily use their own proprietary, advanced spam filtering systems. These systems leverage vast amounts of data, machine learning, and complex algorithms that go far beyond what a static rules-based filter like SpamAssassin can do. While a small number of niche ISPs or individuals who self-host their mail might still use SpamAssassin, it's not the primary gatekeeper for most commercial email traffic.
The idea that a Yahoo or Gmail inbox relies heavily on SpamAssassin rules for deliverability is generally a misunderstanding of how modern email security works. They focus more on sender reputation, content analysis, and user engagement metrics.
SpamAssassin in modern email filtering
SpamAssassin is an open-source solution that relies on a large set of rules. While effective for its design, it lacks the dynamic, adaptive learning capabilities of modern, proprietary systems. It's not a primary filter for major email providers.
Preconnect links and email deliverability
In web development, preconnect links are a performance optimization. They tell the browser to establish an early connection to a third-party domain from which resources, like Google Fonts, will be fetched. This can speed up page loading by initiating DNS lookups, TCP handshakes, and TLS negotiations ahead of time. The specific links for Google Fonts are typically:
However, email clients are not full-fledged web browsers. Their HTML and CSS rendering capabilities are often limited and vary widely. Many email clients do not fully support modern web features, including the HTML link element itself, let alone the preconnect attribute. This means that while these links might be present in your email HTML, they are often ignored or stripped out by the email client.
The claim that the domains are empty/broken is also incorrect. fonts.googleapis.com and fonts.gstatic.com are legitimate, highly reputable Google domains. They serve as content delivery networks (CDNs) for font files. Any SpamAssassin rule flagging these specific domains would be highly unusual and likely indicative of a custom, misconfigured rule set, not a standard one.
Assessing reputation impact
The primary factors affecting email deliverability and how spam filters, including but not limited to SpamAssassin, assess reputation revolve around the sender's domain and IP reputation, email authentication (SPF, DKIM, DMARC), and content quality.
Links can indeed impact deliverability, but typically when they are: excessive, suspicious (e.g., redirecting to known malicious sites), or uncommon (like using mailto links for tracking). Links that point to reputable, well-known domains like Google's font servers are generally not a cause for concern. Many elements can impact email deliverability, including fonts and other design elements, if they are not optimized.
Harmless links
Reputable domains: Links to well-established, trusted sites or CDNs, such as Google Fonts, are unlikely to trigger spam filters.
Direct and clear: Links that are clearly visible and lead to expected content (e.g., an unsubscribe link, product page) are generally safe.
Potentially harmful links
Uncommon or suspicious domains: Links to newly registered, questionable, or known blocklisted (or blacklisted) domains can severely hurt your sender reputation. You can use a blocklist checker to keep an eye on these things.
Excessive links: An overly high number of links, especially short or obfuscated ones, can look like phishing attempts.
Redirects or trackers: Complex redirect chains or links that track too much user behavior can raise red flags for spam filters.
HTTP vs. HTTPS: While less critical than domain reputation, consistently using HTTP instead of secure HTTPS can sometimes be viewed negatively. It's often asked, does using HTTP links affect deliverability?, and generally the answer is yes, stick to HTTPS.
It's highly unlikely that preconnect links for Google Fonts would negatively affect your email sender reputation or cause emails to land in the spam folder, especially with major providers. If a specific SpamAssassin checker is flagging them, it's almost certainly due to a custom, non-standard rule set on that particular checker, not a widely accepted industry best practice or a rule used by Google or other large ISPs.
Strategies for successful email font usage
When using custom web fonts in emails, it's crucial to prioritize compatibility and deliverability over advanced loading optimizations that most email clients simply don't support. The most reliable approach is to include web-safe fonts as fallbacks.
Even if an email client does attempt to render a custom font from Google Fonts, the preconnect hint is unlikely to offer significant performance benefits, if any, unlike in a web browser. The primary concern with Google web font links would be if they led to slow loading times or rendering issues, not direct spam flagging, but even that is rare.
Focus your deliverability efforts on more impactful areas like maintaining a clean mailing list, segmenting your audience, providing relevant content, and ensuring your email authentication records (SPF, DKIM, DMARC) are correctly configured. These are the true foundations of strong email deliverability.
Views from the trenches
Best practices
Always include web-safe font fallbacks to ensure consistent rendering across various email clients, as custom fonts may not display for all recipients.
Prioritize a clean and engaged subscriber list to build positive sender reputation, which is far more critical than minor HTML tags.
Ensure all links in your emails point to legitimate and secure (HTTPS) domains to avoid triggering spam filters.
Monitor your domain and IP reputation regularly to catch any significant issues early and prevent blocklisting (or blacklisting).
Common pitfalls
Over-reliance on complex HTML/CSS features not fully supported by most email clients, leading to broken layouts or ignored styling.
Misinterpreting isolated, niche spam checker results as universal indicators of deliverability issues, especially when they contradict mainstream understanding.
Failing to implement proper email authentication (SPF, DKIM, DMARC), which is a much stronger indicator for major ISPs than font preconnects.
Using too many links or links to suspicious, unknown, or frequently blocklisted (or blacklisted) domains in your email content.
Expert tips
Most email clients ignore <link> tags or strip them out, so preconnect offers no real benefit for email load times or rendering.
Google and other major mailbox providers do not use SpamAssassin as their primary spam filter; their systems are far more advanced.
If a spam checker flags legitimate Google Font domains, it's likely using a custom, outdated, or misconfigured rule set.
Focus on content relevance, sender reputation, and email authentication for true deliverability improvements, not on obscure HTML elements like preconnect.
Marketer view
Marketer from Email Geeks asks why SpamAssassin gives a higher score and why the user believes those specific links are the cause.
2023-12-10 - Email Geeks
Marketer view
Marketer from Email Geeks points out that SpamAssassin is not widely used for filtering email by major providers.
2023-12-10 - Email Geeks
Final thoughts on preconnect links and email reputation
The concern about Google Fonts preconnect links negatively affecting SpamAssassin reputation is largely unfounded. While preconnect links are standard web optimization, they are generally irrelevant within the context of email due to limited client support. The domains fonts.googleapis.com and fonts.gstatic.com are reputable and would not trigger standard spam filters. Additionally, SpamAssassin is not the primary spam filtering mechanism for major email providers like Google.
Removing these preconnect links from your email templates is unlikely to yield any noticeable improvement in email deliverability or SpamAssassin scores, as the original concern appears to stem from a specific, potentially misconfigured, SpamAssassin installation or online checker.
Google and 
Microsoft, primarily use their own proprietary, advanced spam filtering systems. These systems leverage vast amounts of data, machine learning, and complex algorithms that go far beyond what a static rules-based filter like SpamAssassin can do. While a small number of niche ISPs or individuals who self-host their mail might still use SpamAssassin, it's not the primary gatekeeper for most commercial email traffic.
Yahoo or Gmail inbox relies heavily on SpamAssassin rules for deliverability is generally a misunderstanding of how modern email security works. They focus more on sender reputation, content analysis, and user engagement metrics.
