Summary
Google Postmaster Tools (GPT) often shows delivery errors even when emails are ultimately delivered due to various temporary issues. These include soft bounces, greylisting, temporary blocklisting, IP warming challenges, and authentication problems. Documentation from Google and various ESPs confirms that GPT typically logs the initial delivery attempt and resulting errors, regardless of eventual success. Experts and marketers emphasize that GPT data should be viewed as a signal rather than a definitive measure of deliverability, advising reliance on more comprehensive logs and data for accurate assessment.
Key findings
- Temporary Failures: Temporary delivery issues like soft bounces, greylisting, and temporary blocklisting are common causes of reported errors, even if the email is later delivered successfully.
- Initial Attempt Logging: GPT typically logs the initial delivery attempt, which may result in an error, regardless of whether the email is eventually delivered successfully.
- Warming Impact: During IP warming, temporary errors are common and may appear in Postmaster Tools, even when emails eventually get through.
- Authentication Challenges: Authentication problems (SPF, DKIM) can cause initial delivery failures, which are logged even if subsequent retries succeed due to the issues being resolved.
- Inaccurate Percentages: GPT totals aren't always accurate percentages; relying on detailed logs for a reliable source of truth is critical.
- Reputation Hiccups: Temporary reputation hiccups or greylisting can cause initial delivery errors, even if the email delivers on a retry.
Key considerations
- Use GPT as a Signal: Treat GPT data as an indicator, not a definitive measure, of deliverability issues.
- Rely on Comprehensive Logs: Use your own logs and data for a more accurate assessment of email delivery performance.
- Address Temporary Issues: Investigate temporary delivery problems such as soft bounces and greylisting to improve deliverability.
- Implement Authentication: Ensure robust email authentication (SPF, DKIM, DMARC) to reduce initial delivery failures.
- Manage IP Warming: Implement best practices during IP warming to minimize delivery errors and improve initial sender reputation.
- Monitor Reputation: Continuously monitor sender reputation to quickly address issues causing temporary delivery errors.
What email marketers say
13 marketer opinions
Google Postmaster Tools may show delivery errors even when emails are eventually delivered due to several reasons. These include temporary failures during IP warming, initial rejections due to reputation issues or greylisting, temporary server load, temporary blocklisting, authentication problems, and how Postmaster Tools logs initial error instances even if subsequent deliveries are successful. Therefore, Postmaster Tools often reflects the initial state of the delivery attempt, even if the problem is later resolved. The totals are not always accurate percentages and logs should be relied on as the single source of truth.
Key opinions
- Temporary Failures: Temporary failures, like soft bounces or greylisting, are often logged as delivery errors even if the email is later delivered.
- IP Warming: During IP warming, temporary errors are common and may appear in Postmaster Tools even if the emails eventually get through.
- Reputation Issues: Temporary dips in sender reputation can cause initial delivery errors that are logged, even if the sender's reputation recovers.
- Authentication Problems: Initial SPF or DKIM authentication problems can result in logged delivery errors, even if the issues are resolved during retries.
- Logging of Initial Errors: Postmaster Tools logs errors based on the first instance of a delivery issue, and subsequent successful deliveries do not erase the initial error event.
- Greylisting Impact: Greylisting (temporary rejection of emails from unknown senders) can cause initial delivery errors that are recorded by monitoring tools, even when the email is eventually accepted after a retry.
Key considerations
- Temporary vs Permanent: Differentiate between temporary and permanent delivery errors. Temporary errors may resolve on their own.
- Monitor Reputation: Monitor sender reputation to minimize temporary delivery errors.
- Authentication: Ensure proper email authentication (SPF, DKIM, DMARC) to prevent initial delivery failures.
- IP Warming Best Practices: Follow IP warming best practices to avoid triggering initial delivery errors during the warm-up process.
- Postmaster Tools as a Signal: Use Postmaster Tools as a signal, but consider that it might not always provide a complete or real-time view of deliverability.
- Reliance on Logs: The totals provided are not always accurate percentages and logs should be relied on as the single source of truth.
Marketer view
Marketer from Email Geeks mentions temporary failures will show up in Google Postmaster Tools, especially during warming up new clients, but the delivery section may not consistently match actual delivery logs.
21 May 2024 - Email Geeks
Marketer view
Email marketer from Stack Overflow shares that sometimes, temporary failures are reported because of initial rejections due to reputation issues or greylisting, even if the email is delivered later.
23 Mar 2025 - Stack Overflow
What the experts say
3 expert opinions
Experts indicate that Google Postmaster Tools may display delivery errors even when emails eventually reach their destination due to temporary delivery problems such as soft bounces, blocklisting, or greylisting. The tool often records the initial delivery attempt, even if subsequent retries are successful. Due to these inaccuracies, it is recommended to trust your own data and logs over Postmaster Tools alone.
Key opinions
- Inaccurate Data: Google Postmaster Tools data can be inaccurate and may not reflect the final delivery status of emails.
- Temporary Problems: Temporary delivery issues like soft bounces, blocklisting, or greylisting are often the cause of reported errors, even if the email is later delivered.
- First Attempt Logging: Postmaster Tools typically logs the first delivery attempt, which might result in an error, regardless of whether the email is eventually delivered successfully.
Key considerations
- Trust Own Data: Rely on your own data and logs for a more accurate assessment of email delivery performance.
- Temporary Factors: Consider temporary factors like blocklisting or greylisting as potential causes of delivery errors.
- Holistic View: Use Postmaster Tools as part of a holistic deliverability monitoring strategy, but don't rely on it as the sole source of truth.
Expert view
Expert from Spam Resource explains that temporary delivery problems (soft bounces) can be recorded even if the email is later delivered, leading to discrepancies in reports. She mentions temporary blocklisting and greylisting as examples. The system logs the first attempt.
10 Apr 2025 - Spam Resource
Expert view
Expert from Email Geeks explains that Google Postmaster Tool data may be inaccurate and advises to trust your own data and logs.
29 Nov 2023 - Email Geeks
What the documentation says
5 technical articles
According to documentation from multiple email service providers, Google Postmaster Tools shows delivery errors even when emails are eventually delivered because of temporary or transient failures. These failures include deferred deliveries, soft bounces (due to full inboxes or server issues), and other checks that may temporarily defer a message. These initial failures are logged, even if the email is later accepted and delivered successfully.
Key findings
- Temporary Failures Included: Delivery errors in Postmaster Tools include temporary failures like deferred deliveries and soft bounces.
- Initial Failure Reporting: Postmaster Tools often reports the initial failure, even if the email is subsequently delivered.
- Transient Issues: Transient failures, such as full inboxes or temporarily unavailable servers, contribute to reported delivery errors.
Key considerations
- Distinguish Error Types: Understand the difference between temporary and permanent failures to assess the actual impact on deliverability.
- Monitor Transient Issues: Monitor for transient issues that may cause temporary delivery problems.
- Interpret Reporting: Interpret Postmaster Tools reporting in the context of potential temporary failures and not solely as indicators of failed deliveries.
Technical article
Documentation from Microsoft explains that EOP may temporarily defer messages due to various checks. If the messages are later accepted, the initial deferral might still be recorded in monitoring tools, similar to what's observed in Postmaster Tools.
22 May 2024 - Microsoft
Technical article
Documentation from SparkPost explains transient failures, also known as soft bounces. These failures indicate a temporary problem, such as the recipient's mailbox being full or the receiving server being temporarily unavailable. While the email may eventually be delivered, the initial transient failure might still be logged in Postmaster Tools.
30 Dec 2022 - SparkPost
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