Why would Google Postmaster Tools report spam if users aren't complaining?

Google Postmaster Tools (GPP) data often reflects how Google's internal spam filters classify your mail, not just user-reported spam. This can include messages automatically filtered as spam by Google's systems due to various signals, even without direct user complaints.

Can Google's own systems cause legitimate emails to be marked as spam?

Yes, Google has occasionally experienced temporary outages or glitches that cause legitimate email traffic to be incorrectly rejected as spam. If you see a sudden, unexplainable spike that doesn't correlate with your sending, check for industry reports or Google's service status.

Why is there a discrepancy between Google Postmaster Tools and my ESP's spam reports?

If Google Postmaster Tools shows a spam spike but your ESP (like Klaviyo) doesn't, it's likely because Google does not provide direct feedback loops to ESPs for Gmail addresses. GPP reflects Google's internal classification, which is a different data set.

Can DMARC reports help identify the source of unexpected spam rejects?

Yes, DMARC aggregate reports can help identify all sources sending email using your domain, including those you might not be actively managing, or shadow IT . These reports show authentication failures that could contribute to spam flags.

If my spam test (e.g., using GlockApps) passed with flying colors, why would Google still report rejects?

While seed list tests are useful, they may not perfectly replicate Google's complex filtering algorithms or specific user engagement signals. A positive seed list test doesn't guarantee inbox placement for all emails, especially if underlying reputation issues exist or Google has temporary system issues.

Why is Google Partner Program (GPP) reporting spam rejects when no campaigns were sent? - Troubleshooting - Email deliverability - Knowledge base

It can be quite perplexing to see Google Postmaster Tools (GPM) report a high volume of spam rejects, especially on days when your records show no major email campaigns were dispatched. This scenario often leads to confusion and a scramble to pinpoint the root cause.

The immediate reaction might be to question the data or assume an error, particularly if your internal ESP reports indicate low or zero spam complaints for the same period. However, understanding the nuances of how Google processes email and flags spam is crucial here.

The discrepancy between Google's reports and your own campaign data suggests a deeper issue that's not always tied to scheduled marketing sends. It could involve transactional emails, an unforeseen glitch, or other underlying deliverability factors impacting your domain.

Understanding Google's perspective on spam rejects

When Google Postmaster Tools flags spam rejects, it's operating on data gathered directly by Google's receiving mail servers. This is often considered the most authoritative source of truth for Google deliverability, as it reflects how Google's systems perceive your mail, rather than what your sending platform reports.

Unlike some other ISPs, Google does not provide traditional Feedback Loops (FBLs) directly to senders or ESPs that detail individual spam complaints. Therefore, the spam rates you observe in Google Postmaster Tools (GPP) are a unique aggregated metric of user complaints and direct spam classifications by Google's internal filters. This means a low spam complaint rate reported by your ESP, such as

Klaviyo, might not fully align with what GPM indicates.

It is important to remember that a spike in spam rates doesn't always indicate a persistent blacklisting, but rather a temporary block or increased filtering by Google. This can be caused by various factors, including the reputation of your sending IP addresses or domain.

ESP reporting

Visibility: Reports on emails sent through their platform, including bounces and complaints they receive from FBLs where available.
Spam complaints: Reflects direct feedback loops received from some ISPs, but Google does not provide these to ESPs for Gmail addresses.

Google Postmaster Tools (GPP)

Visibility: Shows how Google's internal systems classify your mail, including spam rates and delivery errors to Gmail users.
Spam rejects: Is the definitive data point for Gmail and Google Workspace recipients.

Common culprits behind unexpected spam spikes

The primary reason you might see spam rejects when no marketing campaigns were sent is the presence of other types of email traffic. Many businesses rely on automated emails, such as password resets, order confirmations, shipping notifications, or daily digests. Even low-volume transactional or internal system emails can trigger spam filters if they are misconfigured or if the sending domain's reputation is deteriorating.

Another significant factor, which has occurred in the past, involves internal issues on Google's side. There have been instances where Google's systems inadvertently rejected legitimate email traffic as spam due to temporary glitches or adjustments in their filtering algorithms. In such cases, the problem isn't with your sending practices but with the receiving end. This is a crucial consideration, especially if the issue is short-lived and aligns with known widespread Google outages or issues.

Beyond internal issues, unexpected spam spikes can also be attributed to hitting spam traps, even with low email volume. If your list contains old, inactive, or purchased addresses, you risk encountering these hidden addresses designed to catch spammers. Additionally, hidden or unauthorized sending sources from your domain, perhaps an overlooked system or a compromised account, can also contribute to unexpected spam reports.

Potential causes for unexpected spam rejects

Automated emails: Transactional or system-generated emails impacting reputation.
Google system issues: Temporary glitches or changes in Google's filtering that incorrectly flag legitimate mail.
Spam trap hits: Emails sent to problematic addresses, even at low volume.
Unknown senders: Unauthorized or misconfigured systems sending mail from your domain.
Reputation lag: GPM data reflecting past issues or a slower update cycle.

Diagnosing the issue when no campaigns were sent

To effectively diagnose the issue, a comprehensive approach is required. Start by delving deeper into your Google Postmaster Tools data, looking for specific dates, sending IPs, and any available Feedback-IDs that might provide clues about the source of the rejected mail. This can help you identify if the rejects are coming from your expected ESP or another system.

Next, review your DMARC aggregate reports. While your DMARC pass rate might be high, these reports can reveal legitimate mail streams from sources you weren't aware of, often referred to as shadow IT. Even non-spammy support systems or CRMs, if misconfigured, can contribute to authentication failures that Google might interpret as suspicious. This review can help you map all senders using your domain.

Finally, examine your SMTP logs for any soft bounces or temporary rejections around the dates of the reported spikes. Look for specific error messages, such as 550 5.7.1 unsolicited mail, which directly indicate Google's system blocking your messages due to perceived unsolicited content. This type of error points towards Google's spam filters identifying your email as unwelcome, even if it's transactional. A key resource for this specific bounce issue is Google's help page for unsolicited message errors.

Example Gmail SMTP log entry for an unsolicited message block

550 5.7.1 [Your sending IP] Our system has detected that this message is likely unsolicited mail. To reduce the amount of spam sent to Gmail, this message has been blocked. Please visit https://support.google.com/mail/?p=UnsolicitedMessageError for more information. u5si13059622plg.101 - gsmtp"

Data source	What it reveals	Key insights for unexpected rejects
Google Postmaster Tools	Aggregated spam rates, IP/domain reputation, delivery errors.	Definitive view of how Google perceives your email. Look for specific dates with anomalies.
DMARC reports (aggregate)	All sending sources using your domain, authentication results.	Helps uncover unauthorized or shadow IT sending. Check for unexpected senders.
SMTP logs (from your ESP/MTA)	Detailed delivery responses for individual emails.	Look for specific soft bounces or rejections containing Google's unsolicited message error.

Mitigating future spam rejects and improving deliverability

To prevent future unexpected spam rejects, consistent monitoring and proactive measures are key. Regularly review your Google Postmaster Tools domain reputation to catch any anomalies early. Implement a robust DMARC policy, transitioning to quarantine or reject, to gain full control over who can send email from your domain and prevent unauthorized mail from impacting your reputation.

Ensure that SPF and DKIM authentication records are correctly configured for all legitimate sending sources. Maintaining strong list hygiene by regularly cleaning your email lists of inactive or invalid addresses will also minimize spam trap hits and reduce potential complaints. Focusing on these foundational elements will significantly boost your overall email deliverability.

Best practices for ongoing deliverability

Proactive monitoring: Check Google Postmaster Tools daily for any changes in spam rates.
DMARC enforcement: Move to a p=quarantine or p=reject policy to protect your domain.
Authentication check: Verify SPF and DKIM records for all sending services are correct.
List hygiene: Regularly remove inactive or unengaged subscribers from your lists.

Views from the trenches

Best practices

Always check the dates in Google Postmaster Tools against your actual sending logs, including automated emails.

Verify all sending sources, even those not directly controlled by your marketing team, using DMARC reports.

Regularly review your SMTP logs for specific bounce codes from major ISPs like Google to catch issues early.

Be aware of widespread ISP issues or outages that might temporarily affect your deliverability metrics.

Common pitfalls

Mistaking low ESP-reported spam complaints for complete inbox placement success with Google.

Ignoring transactional or automated email sends when troubleshooting deliverability issues.

Assuming high DMARC pass rates mean no other senders are impacting your domain reputation.

Failing to cross-reference Google Postmaster Tools data with other deliverability indicators.

Expert tips

If Google reports show a spike, but no campaigns were sent, investigate automated mail flows.

Google's own system issues can sometimes cause legitimate emails to bounce, so monitor industry news.

Feedback-ID in Gmail can help identify the campaign or email type causing spam complaints.

Confirm that your DMARC reports show all mail streams from your domain, not just campaign sends.

Marketer view

Marketer from Email Geeks says they saw a huge reject from GPM when no campaigns were sent, only usual automation emails. Their DMARC reports showed nothing out of the ordinary, and a spam test passed. Klaviyo's reported spam also did not indicate a huge complaint.

2022-02-19 - Email Geeks

Expert view

Expert from Email Geeks says that Google doesn't send back FBLs, so GPT is the source of truth for spam complaints. Delivery errors would indicate some traffic being bounced, and checking the Feedback-ID in GPT might reveal the source if it's not Klaviyo.

2022-02-19 - Email Geeks

Staying ahead of unexpected deliverability challenges

Experiencing spam rejects in Google Postmaster Tools when you haven't sent any active campaigns can be unsettling, but it's a common scenario with identifiable causes. Whether it's due to automated email flows, Google's internal system anomalies, or overlooked sending sources, the key lies in methodical investigation.

By leveraging Google Postmaster Tools, DMARC reports, and your SMTP logs, you can often pinpoint the exact reason for these unexpected spikes. A proactive approach to email deliverability, including stringent authentication and list hygiene, will help you maintain a strong sending reputation and avoid future disruptions.