Why are some domains showing a temp fail in Gmail Postmaster after the Gmail outage?
Matthew Whittaker
Co-founder & CTO, Suped
Published 30 Jul 2025
Updated 19 Aug 2025
7 min read
Experiencing temporary email failures in Gmail Postmaster Tools (or GMT) can be concerning, especially when it appears unexpectedly after an event like a widespread Google outage. Many senders closely monitor their domain reputation and delivery metrics, so any deviation, even a small percentage of temp fails, warrants investigation.
It is important to understand what these temporary failures signify and how to differentiate between a minor fluctuation and a more serious underlying deliverability issue. While an outage can indeed cause transient problems, other factors commonly contribute to these errors, requiring a nuanced approach to troubleshooting.
Interpreting temporary failures in Gmail Postmaster Tools
A 'temp fail' in Postmaster Tools typically refers to a 4xx SMTP error, which indicates a temporary issue preventing email delivery. Unlike a permanent failure (5xx error), which means the email will not be delivered, a temporary failure suggests that the mail server will retry sending the message later. These errors can stem from various sources, including recipient server overload, greylisting, or transient network problems.
Postmaster Tools provides valuable insights into your email program's performance with Gmail users, offering dashboards for sender reputation, spam rate, delivery errors, and authentication. When you see an uptick in temp fails labeled as 'suspect spam', it means Gmail temporarily deferred your emails because they exhibited characteristics that raised spam flags.
This deferral can be a subtle warning sign, even if the percentage is low. While it doesn't immediately translate to permanent rejections or blacklisting (or blocklisting), it suggests that your sending practices or content might be approaching a threshold that Gmail's filters deem suspicious. Constant monitoring of these trends is crucial to prevent further escalation.
Post-outage impact on email delivery
A major outage at a large email service provider like Google can have ripple effects on email delivery. During an outage, a provider's systems may struggle to process incoming mail at their usual rate, leading to temporary backlogs and deferred deliveries. This can manifest in Postmaster Tools as an increase in temporary failures as their servers temporarily throttle or defer mail to cope with the disruption.
Even after the immediate outage is resolved, it can take some time for mail flow to normalize. Post-outage recovery might involve a period where systems are still catching up, or where temporary rate limits remain in place to prevent a new overload. This transient period can result in lingering temporary failures, which may not indicate a problem with your specific sending practices but rather the broader network's recovery process.
If you observe a sudden, widespread increase in temp fails across multiple domains, all starting around the time of a known outage, it is highly probable that the two events are related. However, it's still prudent to cross-reference with other deliverability metrics to confirm this hypothesis and rule out any other concurrent issues on your end.
Identifying other causes of temporary failures
While a Gmail outage can explain some temporary failures, it is essential to consider other common causes that might contribute to or exacerbate the issue. Often, these errors are a symptom of broader deliverability challenges that need addressing.
Authentication failures
One of the most frequent reasons for temporary failures, especially those flagged as 'suspect spam,' relates to email authentication. If your Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), or Domain-based Message Authentication, Reporting & Conformance (DMARC) records are misconfigured, or if your emails fail alignment checks, recipient servers are more likely to temporarily reject (greylist) or defer your messages.
Gmail and other major mailbox providers rely heavily on these authentication standards to verify the legitimacy of incoming mail. A failure here can significantly impact your sender reputation and lead to an increase in temporary or even permanent rejections. Ensuring proper setup and alignment of SPF, DKIM, and DMARC is paramount for healthy deliverability.
Sender reputation and content issues
Beyond authentication, your sender reputation plays a critical role. Factors like high spam complaint rates, low engagement (opens and clicks), sending to invalid or inactive addresses, or rapidly increasing send volume without proper warming up can all lead to Gmail (and other ISPs) temporarily limiting your mail. The content of your emails, including suspicious links or keywords commonly associated with spam, can also trigger these temporary deferrals.
Proactive measures to improve deliverability
When facing temp fails, whether post-outage or due to other factors, a systematic approach to troubleshooting is essential. The goal is to minimize these temporary rejections and ensure your emails consistently reach the inbox.
Monitoring Postmaster Tools
Regularly check your Postmaster Tools dashboards, specifically the Delivery Errors dashboard. Pay attention to trends rather than isolated spikes. If the percentage of temp fails remains consistently low (e.g., below 0.5%) and doesn't lead to permanent bounces, it might be less critical. However, any sustained increase warrants a deeper dive.
Reviewing authentication and content
Verify your SPF, DKIM, and DMARC records for proper configuration and alignment. Use a third-party tool to double-check their validity. Additionally, analyze your email content for anything that might appear spammy, such as excessive links, suspicious phrasing, or poor formatting. A/B test different content variations to see if it impacts your deliverability.
Adjusting sending volume and list hygiene
If you recently increased your sending volume, consider gradually scaling it back to allow your domain reputation to adapt. Crucially, maintain excellent list hygiene by regularly cleaning your email lists, removing inactive subscribers, and promptly addressing any bounce messages. Sending to unengaged or invalid addresses can significantly harm your sender reputation.
The path to better deliverability
Best practices
Regularly monitor Gmail Postmaster Tools for any shifts in delivery error rates.
Ensure your SPF, DKIM, and DMARC records are correctly configured and aligned.
Segment your email lists and tailor content to improve engagement and reduce spam reports.
Gradually increase sending volume for new domains or IPs to build a positive reputation.
Implement a double opt-in process to build a highly engaged and clean subscriber list.
Common pitfalls
Ignoring minor upticks in 'temp fail' rates can lead to a long-term decline in reputation.
Failing to review email content for spam triggers like suspicious links or excessive images.
Sending to unengaged or inactive subscribers can negatively impact your sender score.
Rapidly increasing email volume without proper domain or IP warming practices.
Overlooking DMARC authentication failures that contribute to temporary rejections.
Expert tips
Analyze email metrics beyond delivery rate; focus on engagement, complaints, and bounces.
Leverage Gmail Postmaster Tools for actionable data on deliverability and sender reputation.
Set up alerts for significant changes in deliverability metrics to enable quick response.
Regularly prune your email list to remove invalid or unengaged addresses.
Continuously test and optimize email campaigns to maintain high sender reputation.
Marketer view
Marketer from Email Geeks says, some domains on Gmail Postmaster are showing a small percentage of temp fail suspect spam, which started around the 27th, despite having high reputation previously.
2023-02-28 - Email Geeks
Marketer view
Marketer from Email Geeks says that while they observe temp fails for a few clients, they are not concerned as these are temporary and other metrics remain stable.
2023-02-28 - Email Geeks
Temporary failures in Gmail Postmaster Tools can be perplexing, especially when they appear after a significant event like a Gmail outage. While such outages can certainly contribute to transient deliverability issues, it is rare for them to be the sole cause of sustained problems.
The key is to adopt a proactive approach, consistently monitoring your Postmaster Tools data, ensuring your authentication records are solid, and adhering to email marketing best practices. By doing so, you can quickly identify and address potential issues, maintain a healthy sender reputation, and improve your overall email deliverability to Gmail users.
