How do I fix Gmail deliverability issues when emails are going to spam folders?
Matthew Whittaker
Co-founder & CTO, Suped
Published 29 Apr 2025
Updated 18 Aug 2025
8 min read
Emails going to spam folders in Gmail is a frustrating but common challenge for senders. You might have excellent content and a dedicated IP, yet your messages aren't reaching the primary inbox. This issue often stems from a complex interplay of technical configurations, sender reputation, and recipient engagement patterns that Google's sophisticated filtering system uses.
Recent changes announced by Gmail and Yahoo (or Oath) for 2024 and 2025 further emphasize the critical need for proper email authentication, low spam rates, and easy unsubscribe options. These updates mean that even legitimate emails risk landing in the spam folder if they don't meet the enhanced requirements. It's no longer enough to just send emails, you must actively ensure they are delivered.
If you are struggling with Gmail deliverability and finding your emails consistently filtered into spam, a systematic approach is essential. This guide will walk you through the key areas to investigate and the steps you can take to diagnose and resolve these issues, helping your messages reach the inbox as intended.
Ensuring proper email authentication
A strong foundation in email authentication protocols, such as SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail), is non-negotiable for reliable deliverability. These records verify that your emails are legitimately sent from your domain, preventing spoofing and unauthorized use. However, having them "in place" isn't always enough, they must be correctly configured to align with your sending practices.
The critical third component is DMARC (Domain-based Message Authentication, Reporting, and Conformance). If you have SPF and DKIM but lack DMARC, you're missing a vital layer of security and visibility into your email ecosystem. DMARC tells receiving mail servers what to do if an email fails SPF or DKIM checks, and it provides reports that show exactly how your emails are being authenticated across the internet. Without DMARC, you're essentially sending emails blind, without a clear understanding of your authentication failures, which is often a root cause of emails landing in spam.
Furthermore, ensuring your DKIM signing envelope is customized to sign on your sending domain, rather than your email service provider's domain, is crucial for full DMARC alignment. This technical detail ensures that your domain's reputation directly benefits from successful authentication. Here is an example DMARC record:
Building and maintaining a strong sender reputation
Gmail heavily relies on sender reputation to decide whether to place an email in the inbox, promotions tab, or spam folder. Your reputation is influenced by various factors, including spam complaints, bounce rates, IP reputation, and engagement metrics. Even if your emails aren't on a public blacklist (or blocklist), your sender reputation with Gmail can still be low.
Google Postmaster Tools (GPT) is an invaluable, free resource for monitoring your sender reputation with Gmail. It provides data on IP and domain reputation, spam rates, feedback loops, and authentication errors. If data isn't populating in your GPT account, it often indicates an issue with your DKIM setup not being properly aligned or sufficient email volume being sent to Gmail accounts. Low engagement rates, particularly low open rates at Gmail, are a strong signal that your emails are not performing well and may be landing in spam.
Your sending volume and the percentage of your contact base that is Gmail also play a role. If a significant portion of your emails go to Gmail users and your engagement metrics are low, Gmail's filters will be more inclined to direct your messages to the spam folder. Proactively checking your domain for blocklist presence can help rule out some issues, but private blacklists (or blocklists) used by Gmail are not publicly accessible.
Low engagement warning
A consistently low open rate, especially at Gmail (e.g., around 4%), is a major red flag. This indicates that your emails are likely bypassing the inbox and heading straight to spam, leading to poor sender reputation with Google. Addressing this requires immediate action on your sending strategy and list hygiene.
Optimising email content and recipient engagement
Beyond technical setup and reputation, the content of your emails and how your recipients engage with them significantly impact Gmail's spam filtering. While image-heavy emails aren't inherently problematic if they're relevant, excessive use or poor image-to-text ratio can sometimes be a trigger. Review your content for spammy keywords, unusual formatting, or overly promotional language that might raise red flags.
One of the most impactful strategies is to prioritize sending to your most engaged subscribers. If your emails are consistently sent to inactive users, it tells Gmail that your content isn't valuable, which can lead to lower inbox placement. Segmenting your audience and focusing on those who have recently opened or clicked your emails can dramatically improve your engagement metrics and, consequently, your sender reputation with Gmail. This practice helps to improve overall email deliverability rates.
Clean up your email list regularly by removing hard bounces, soft bounces, and inactive subscribers who haven't engaged in months. Spam traps, which are email addresses used by internet service providers (ISPs) to catch spammers, can severely damage your reputation. Sending to them is a clear sign of poor list hygiene and can result in immediate blacklisting or blocking. Here’s a comparison of good versus bad engagement practices:
Good engagement practices
Active subscribers: Focus on sending to recipients who have opened or clicked your emails recently, ideally within the last 2-4 weeks, to signal high relevance.
Personalization: Tailor content to individual preferences, which increases the likelihood of opens and clicks.
Clear CTAs: Use compelling and easy-to-understand calls to action that encourage recipient interaction.
Bad engagement practices
Inactive lists: Sending to subscribers who haven't engaged in six months or longer can significantly harm your sender reputation.
High bounce rates: Repeatedly sending to invalid email addresses signals poor list management and can trigger spam filters.
Generic content: Emails that lack personalization or relevance lead to low engagement and higher spam complaints.
Advanced diagnostics and recovery
When facing persistent Gmail deliverability issues, a comprehensive audit of your email program is necessary. Start by segmenting your Gmail recipients and analyzing their engagement metrics over time. If you observe a decline, or if your open rates are consistently below industry benchmarks, it's a strong indicator that you need to adjust your sending strategy. One effective tactic is to pull back your sending volume to only those who have engaged recently, for example, within the last two weeks or even seven days.
Remediating a damaged Gmail sender reputation takes time and consistent effort. Gmail's filters learn from continuous positive engagement. This means that after implementing changes, you may need several weeks of sending to a highly engaged audience before seeing significant improvements in inbox placement. Patience and persistence are key here, as there's no instant fix for reputation issues.
Continuously monitor your DMARC reports to identify any ongoing authentication failures. These reports provide valuable insights into where your emails are failing authentication checks and can help you pinpoint specific issues. Also, review your Google Postmaster Tools dashboards daily, paying close attention to your spam rate, IP reputation, and domain reputation. These metrics will tell you if your efforts are yielding positive results.
Remember, email deliverability is an ongoing process, not a one-time fix. Regularly auditing your practices, staying updated with Gmail's sender guidelines, and prioritizing recipient engagement are crucial for sustained inbox placement. For further insights on general deliverability troubleshooting, consider exploring a comprehensive guide to diagnosing email issues.
Views from the trenches
Best practices
Implement DMARC at a 'p=none' policy initially to gain visibility into your email authentication.
Monitor Google Postmaster Tools daily for spam rates, IP, and domain reputation metrics.
Segment your audience and focus on sending to the most engaged recipients.
Prioritize list hygiene by regularly removing inactive subscribers and hard bounces.
Common pitfalls
Neglecting DMARC implementation, which leaves you blind to authentication failures.
Sending to an entire list, including unengaged or inactive subscribers, which degrades sender reputation.
Ignoring low open rates and spam complaints in Gmail Postmaster Tools.
Relying solely on being off public blacklists (or blocklists) without addressing private ISP blacklists.
Expert tips
Consider reducing sending volume to only those who have engaged within the last 7-14 days.
Expect remediation to take several weeks of consistent good sending practices.
Ensure your DKIM signing aligns with your sending domain, not just your ESP's domain.
Review email content for any elements that might trigger spam filters, even if not explicitly spammy.
Expert view
Expert from Email Geeks says to establish several performance barometers, including open rates at Gmail, average daily, weekly, and monthly volume, and the percentage of your contact base that consists of Gmail users. These metrics are crucial for initial assessment.
February 1, 2019 - Email Geeks
Marketer view
Marketer from Email Geeks says that their brand typically sees an overall open rate of 6-8%, with Gmail open rates around 4% for a monthly volume of 600,000 emails, targeting a contact base that is just over half Gmail.
February 2, 2019 - Email Geeks
Charting your path to the inbox
Resolving Gmail deliverability issues requires a multifaceted approach that combines technical rigor with strategic audience engagement. From ensuring your authentication protocols (SPF, DKIM, and especially DMARC) are perfectly configured, to diligently monitoring your sender reputation through tools like Google Postmaster Tools, every detail matters. The goal is to build trust with Gmail's filters, signaling that you are a legitimate and valued sender.
Ultimately, your emails will only reach the inbox if they are relevant and desired by your recipients. Prioritizing engagement, maintaining a clean and active email list, and adjusting your sending frequency based on performance are all crucial steps. Remember that improving deliverability is an ongoing journey of continuous optimization and learning.
By implementing these strategies and consistently monitoring your performance, you can significantly improve your Gmail inbox placement and ensure your messages reach their intended audience, rather than getting caught in the spam folder. Consistent effort in these areas will yield long-term benefits for your email program.
