How do I interpret 'Rejected' errors in Gmail Postmaster Tools?
Matthew Whittaker
Co-founder & CTO, Suped
Published 30 Apr 2025
Updated 17 Aug 2025
7 min read
When you're managing email campaigns or transactional emails, seeing a high percentage of "Rejected" errors in your Gmail Postmaster Tools (GPT) Delivery Errors dashboard can be alarming. This metric signals that Gmail is outright refusing to accept your messages, rather than just placing them in the spam folder. Understanding these rejections is crucial for maintaining good email deliverability.
The Delivery Errors report in Postmaster Tools provides a percentage of all authenticated messages (SPF or DKIM) that were rejected or temporarily failed. If you see a spike in rejected traffic, it indicates a significant issue that needs immediate attention because these emails are not reaching their intended recipients at all.
I'll guide you through interpreting these rejected errors, identifying their common causes, and outlining the steps you can take to mitigate them. It’s essential to look beyond just the percentage and try to understand the underlying reasons for the rejections to effectively improve your sending reputation and inbox placement.
Understanding the 'rejected' error in Postmaster Tools
When Gmail Postmaster Tools (GPT) shows 'Rejected' errors, it means the email was blocked at the SMTP (Simple Mail Transfer Protocol) level. This is different from emails being marked as spam or delivered to the junk folder. A rejection is a hard block, indicating that the Gmail server refused the connection or the message itself from your sending IP or domain.
The Postmaster Tools dashboard aggregates various types of delivery failures into this Rejected category. These rejections often come with 550 series SMTP error codes, which signify permanent failures. For example, a 550 5.7.1 can indicate a policy rejection, meaning Gmail determined the message violated its sending policies or that your domain (or IP) has a very low reputation.
It’s important to differentiate 'Rejected' from 'TempFail'. While both are delivery errors, TempFail (indicated by a 4xx SMTP code) means the email was temporarily deferred due to issues like a busy server or rate limiting, and typically the sending server will retry delivery. Rejection means no retries will occur, the email is definitively not delivered.
Common causes for email rejection
Several factors can lead to your emails being rejected by Gmail. The most common reasons revolve around your sender reputation, authentication status, and the content of your emails.
One primary cause is a low sender reputation. Gmail (and other mailbox providers) assign a reputation score to both your sending IP address and your domain. If your reputation is low or bad, Gmail is more likely to reject your messages outright, especially if it suspects a high volume of unsolicited email. This is particularly true if your IP or domain appears on an email blocklist (or blacklist).
Inadequate email authentication also plays a significant role. Gmail requires proper SPF, DKIM, and DMARC setup. If your emails fail these checks, they are often rejected as unauthenticated. For example, if SPF fails, it signals that the sending server is not authorized to send mail on behalf of your domain. Similarly, DMARC with a p=reject policy can lead to immediate rejections if alignment fails. Finally, the content of your emails might trigger spam filters, leading to rejections if it contains suspicious-looking or spammy text.
Furthermore, a sudden influx of emails to invalid or non-existent addresses (sometimes due to purchased or old lists) can trigger rejections, as this behavior resembles that of spammers trying to find valid email addresses. Using a reputable Email Service Provider can help you manage these issues.
Diagnosing the root cause of rejections
To effectively address rejected emails, you need to dive deeper than just the Postmaster Tools dashboard. While GPT shows you the percentage, your own bounce logs provide the specific SMTP error codes and messages that reveal the exact reason for the rejection.
Start by correlating the dates of spikes in rejected errors in GPT with your internal email logs. Look for hard bounces (often 5xx errors) specifically from Gmail recipients. Pay attention to the accompanying diagnostic messages. These messages might indicate if the rejection was due to reputation issues, content flags, or authentication failures. For instance, a 550 5.7.1 error often points to sender policy violations or a poor domain reputation.
Check your sender reputation dashboards in GPT for both your IP and domain. If they are showing 'Low' or 'Bad', it’s a strong indicator that reputation is the primary factor. Also, review your Spam Rate dashboard; a high spam complaint rate can quickly degrade your reputation and lead to rejections.
Example of a common Gmail rejection messagetext
550 5.7.1 [IP address] Our system detected an unusual rate of unsolicited mail originating from your IP address. To protect our users from spam, mail sent from your IP address has been temporarily blocked. Please visit https://support.google.com/mail/?p=UnsolicitedIPError to review our Bulk Sender Guidelines.
Steps to resolve rejected emails
Once you've identified the likely cause of your rejected errors, it's time to implement solutions. The path to recovery depends on the underlying issue, but generally involves improving sending practices and ensuring proper technical configurations.
Causes of rejection
Low reputation: Your IP or domain has accumulated a poor sending history, often due to high spam complaints or sending to invalid addresses.
Authentication failures: Missing or misconfigured SPF, DKIM, or DMARC records.
Spammy content: Gmail's filters detect patterns indicative of unsolicited mail in your message content or subject lines.
If reputation is the problem, focus on building positive sending habits. This includes sending wanted mail, maintaining a clean list by removing invalid or inactive addresses, and responding to spam complaints promptly. It takes time to rebuild a damaged reputation, but consistent good practices will eventually improve your standing with Gmail.
For authentication issues, ensure your DNS records for SPF, DKIM, and DMARC are correctly set up and aligned. Use a DMARC policy of p=none to monitor authentication failures first, then gradually move to p=quarantine or p=rejectas you gain confidence. Regular monitoring of your DMARC reports can help you catch these issues early. If blocklisting is an issue, you'll need to identify which blacklist (or blacklists) you're on and follow their specific delisting procedures. This typically involves fixing the underlying problem that led to the listing (e.g., removing a spam trap, reducing complaints) before requesting removal.
Key takeaways
Understanding "Rejected" errors in Gmail Postmaster Tools requires a multi-faceted approach. It's not just about seeing the percentage, but about digging into the root causes, which often involve sender reputation, email authentication, and content quality. By proactively monitoring your Postmaster Tools data, analyzing bounce logs, and implementing best practices, you can effectively resolve these issues and improve your email deliverability to Gmail recipients.
Consistent vigilance and adherence to email best practices are key to maintaining a healthy sender reputation and ensuring your important messages reach the inbox, avoiding those frustrating rejections.
Views from the trenches
Best practices
Maintain a healthy sender reputation by sending relevant, wanted emails to engaged subscribers.
Regularly monitor your Gmail Postmaster Tools dashboards, especially Delivery Errors, IP and Domain Reputation.
Ensure SPF, DKIM, and DMARC are properly configured and aligned for your sending domains.
Segment your email lists and send targeted content to minimize spam complaints and rejections.
Common pitfalls
Ignoring "Rejected" errors, assuming they are just soft bounces or spam folder deliveries.
Not correlating Postmaster Tools data with internal bounce logs for specific SMTP error messages.
Sending emails to old or unverified lists, leading to high bounce rates and spam trap hits.
Making drastic changes to sending volume or content without gradual warming up.
Expert tips
The Postmaster Tools 'Rejected' percentage is an aggregate; click on the specific data point to see if Gmail provides a breakdown of error types below the graph.
A sudden spike in rejections without a corresponding increase in your bounce logs could indicate temporary Gmail deferrals (TempFails) that eventually bounced or were never retried by your ESP.
If your bounces are mostly 'Mailbox Unavailable' or 'Invalid Inbox (typos)', the Postmaster Tools 'Rejected' error might be highlighting issues with list hygiene, even if your total bounce rate isn't drastically higher.
For very low sending volumes, Postmaster Tools may not show data, making it harder to diagnose rejections solely from there.
Marketer view
Marketer from Email Geeks says they assume they need to narrow down their bounce logs to only include @gmail.com inboxes to find the specific issues behind the rejections.
2023-08-25 - Email Geeks
Marketer view
Marketer from Email Geeks says that if bounce logs indicate invalid inboxes (typos) or 'Mailbox Unavailable' errors, it's puzzling why Postmaster Tools would specifically highlight those days in the log.
