How do broken links impact Gmail deliverability during domain warming?
Michael Ko
Co-founder & CEO, Suped
Published 19 Jun 2025
Updated 13 Oct 2025
6 min read
Starting a new email sending domain involves a crucial process called domain warming. This involves gradually increasing your email volume over time, allowing mailbox providers (MBPs) like Gmail and Yahoo to build trust in your sending habits. It's akin to building a credit score for your email, establishing a positive domain reputation.
During this sensitive warming period, every aspect of your email campaigns is under a microscope. Even seemingly minor issues can have a disproportionately negative impact on deliverability. My experience has shown that something as overlooked as a broken link can significantly derail your warming efforts, especially with discerning providers like Gmail.
While you might diligently check email authentication protocols like SPF, DKIM, and DMARC, links often escape such rigorous scrutiny. However, these small details contribute to the overall perception of your email's legitimacy and quality.
The direct impact on sender reputation
Mailbox providers are constantly evaluating incoming mail for signs of spam or poor sending practices. A broken link, or a dead URL, within an email can be interpreted as a negative signal. It suggests a lack of attention to detail, a potentially compromised sender, or even a phishing attempt if the link points to a suspicious or non-existent destination.
For Gmail, which employs highly sophisticated filtering algorithms, these signals are amplified, especially during domain warming. A new domain is already under increased scrutiny to ensure it's not a source of malicious or low-quality mail. When a new domain sends emails containing broken links, it directly impacts the nascent sender reputation. This can quickly trigger spam filters, leading to poor inbox placement, or even direct delivery to the spam folder.
I've seen firsthand how an otherwise perfectly configured email stream, with all authentication passing, can struggle with Gmail because of something as simple as a few broken links in the footer. It’s a subtle indicator that can have a severe ripple effect on your overall email deliverability.
The silent reputation killer
During domain warming, your new sending subdomain lacks historical data, making it highly susceptible to negative signals. A single broken link can dramatically lower your domain's reputation with Gmail, leading to a sudden shift from inbox to spam folders for a significant portion of your audience. This can stall or even reverse your warming progress, making it much harder to reach your audience.
Understanding domain reputation and warming sensitivity
Domain reputation is the foundation of successful email marketing. It’s how mailbox providers like Gmail assess the trustworthiness of your sending domain. A higher reputation means better inbox placement, while a lower one means more messages end up in the spam folder or are rejected entirely. Domain warming is precisely the process of cultivating this good reputation by gradually increasing sending volume while maintaining positive engagement.
When you introduce a new subdomain for sending, it starts with a neutral, or sometimes slightly positive, reputation. Every interaction, every engagement, and every technical detail in your emails contributes to building (or harming) this reputation. Broken links, especially those in critical areas like the footer (e.g., unsubscribe links, privacy policy), can be a serious red flag. They suggest that your email is either poorly maintained or potentially deceptive, both of which are major deterrents for Gmail's spam filters.
In a recent situation I encountered, a client’s domain reputation with Google Postmaster Tools (GPT) plummeted from high to low within a day of starting warming, despite all standard authentication passing. The culprit, discovered through deeper investigation, was a broken link. This swift degradation in reputation highlights how sensitive Gmail is during the warming phase, treating even seemingly minor issues as significant indicators of sender quality.
Gmail heavily weighs user interaction, low opens/clicks suggest unwanted mail.
Spam complaints
One of the strongest negative signals, directly impacting sender reputation.
Unverified mailing lists
Leads to high bounce rates and potential spam trap hits.
Practical steps to identify and fix broken links
The good news is that broken links are a fixable issue. The key is to be proactive. Before you even start your warming process, or certainly as an immediate step if you encounter deliverability issues, thoroughly check all links within your email templates. This includes links in the header, body, and especially the footer, which can often be overlooked.
You can use various online link checkers or even simple manual checks. Pay attention to how Gmail (and other MBPs) handles specific link types, such as redirects, URL shorteners, and the protocol used (HTTP vs HTTPS). Ensure that any tracking links are also functional and don't lead to errors.
Once a broken link is identified, update it to the correct, active URL. In the case I mentioned, simply fixing a broken footer link immediately resulted in open rates returning to expected levels within Gmail. This demonstrates the immediate and tangible benefit of addressing such issues. Consistency and vigilance are paramount throughout your warming period and beyond.
Wait for issues: Only check links after noticing deliverability drops or spam folder placement.
Manual spot checks: Inconsistent checks that may miss deeper problems.
Delayed recovery: Takes longer to identify and resolve, prolonging poor performance.
Proactive approach
Pre-send validation: Integrate link validation into your pre-send checklist.
Automated scanning: Utilize tools that automatically scan emails for broken links.
Faster warming: Prevents setbacks and allows for smoother domain warming.
Beyond broken links: other considerations for Gmail warming
While fixing broken links is a critical step, it's important to remember that it's just one piece of the complex email deliverability puzzle. To ensure consistent inbox placement, especially with Gmail, you need a holistic approach that covers several key areas.
Content quality and recipient engagement play a significant role. Gmail highly values how recipients interact with your emails. If your emails are engaging, opened, and clicked, it signals to Gmail that your content is desired. Conversely, high spam complaint rates or low engagement can quickly damage your domain's reputation.
Regular list hygiene is also vital. Sending to invalid or inactive email addresses can lead to hard bounces and hit spam traps, both of which severely harm your sender reputation. Combining these best practices with diligent link management will pave the way for successful domain warming and sustained deliverability.
Comprehensive deliverability best practices
Maintain high engagement: Send relevant content to active subscribers to encourage opens and clicks.
Segment your audience: During warming, send to your most engaged subscribers first.
Ensure proper authentication: Verify your SPF, DKIM, and DMARC records are correctly configured.
Clean your list regularly: Remove inactive or invalid addresses to prevent bounces and spam traps.
Views from the trenches
Best practices
Actively monitor your domain's reputation using tools like Google Postmaster Tools throughout the warming process to catch any sudden drops.
Implement a robust pre-send checklist that includes automated link validation to catch broken links before they go out.
Prioritize sending to highly engaged segments of your list during domain warming to build positive engagement signals.
Regularly review your email templates for any outdated or potentially problematic links, especially those in footers.
Common pitfalls
Assuming that only SPF, DKIM, and DMARC matter, overlooking content quality and link validity as key reputation factors.
Ignoring a drop in open rates, particularly with Gmail, and attributing it solely to warming pains without deeper investigation.
Not thoroughly checking all links, including those in privacy policies or unsubscribe footers, which can often be forgotten.
Rushing the warming process by sending too much volume too quickly, making any negative signals even more impactful.
Expert tips
If your open rates are drastically lower for one MBP (like Gmail) but fine elsewhere, investigate differences in how that MBP processes or caches content.
Consider that Google's prefetching of images might impact reported open rates differently for new versus old domains.
Understand that domain warming can be an emotional journey, and sometimes you just need to power through temporary valleys in performance.
Always fix any broken links immediately upon discovery, as even minor issues can have an outsized negative impact, especially during warming.
Marketer view
Marketer from Email Geeks says they identified a broken link in their email's footer which caused a new sending subdomain's Gmail open rates to plummet, despite other MBPs performing well. Fixing the link immediately resolved the issue.
2022-03-18 - Email Geeks
Expert view
Expert from Email Geeks says that a new subdomain combined with 404 links, such as those for privacy or unsubscribe pages, will negatively affect the reputation of that specific mail stream.
2022-03-18 - Email Geeks
Navigating domain warming with precision
The journey of domain warming requires meticulous attention to detail, and broken links, though seemingly minor, can create significant roadblocks, especially with a strict recipient like Gmail. My experience has shown that these errors are not just an inconvenience but a genuine threat to your sender reputation and overall email deliverability.
By proactively identifying and fixing any broken links, alongside maintaining strong email authentication and engaging content, you can navigate the complexities of domain warming more smoothly. This vigilance ensures that your emails consistently land in the inbox, fostering trust with your audience and mailbox providers alike.
