Summary
The 5.7.1 'Delivery not authorized' error in Gmail, specifically due to duplicate headers, is a multifaceted issue stemming from Gmail's stricter enforcement of RFC 5322 and SMTP standards. Duplicate headers (such as To, From, Date, and Message-ID) violate these standards, leading to message rejection. The error often indicates policy violations, unusual sending patterns, authorization problems, or underlying SMTP errors. Contributing factors can include special characters in the 'friendly from' field, manual header construction, and the presence of spam-like content. Resolving this involves ensuring strict RFC 5322 compliance, correcting invalid, malformed, or duplicated header fields, employing proper email sending libraries, and adhering to best practices for email deliverability.
Key findings
- RFC 5322 Enforcement: Gmail's stricter enforcement of RFC 5322 is a primary driver for 5.7.1 errors related to duplicate headers.
- Duplicate Headers: Headers like To, From, Date, and Message-ID are key culprits when duplicated.
- SMTP Errors: The 5.7.1 error often signals underlying SMTP errors related to malformed or invalid headers.
- Policy Violations: Gmail's sending policies, security settings, and unusual patterns can contribute to this error.
- Spam Indicators: Content characteristics and spam-like markers lead to trigger of the 5.7.1.
Key considerations
- RFC Compliance: Ensure that all email headers are compliant with the RFC 5322 standard, avoiding any duplication.
- Message-ID Uniqueness: Confirm that each email message has a unique Message-ID header.
- SMTP Field Correction: Identify and correct any malformed, invalid, or duplicated header fields in the SMTP settings.
- Friendly From Sanitization: Review the 'friendly from' field and remove any special characters that could cause parsing issues.
- Automated Header Generation: Use email sending libraries or services to automate header generation and prevent manual errors.
- Implement Correct Practices: By implementing email practices, sending servers will no longer reject.
What email marketers say
10 marketer opinions
The 5.7.1 delivery not authorized error in Gmail, specifically related to duplicate headers, arises from Gmail's strict enforcement of RFC 5322 standards. Duplicate headers (like To, From, Date) are a common cause. The issue often indicates policy violations, unusual sending patterns, or security concerns. Resolving it involves ensuring RFC 5322 compliance, avoiding spam-like content, using proper email sending libraries, and reviewing email sending practices. Special characters in the 'friendly from' field and manual header construction can also contribute to this error.
Key opinions
- RFC 5322 Violation: Gmail is strictly enforcing RFC 5322 compliance, causing rejections for duplicate headers.
- Header Duplication: Duplicate headers like 'To', 'From', and 'Date' are common causes of the 5.7.1 error.
- Policy Violation: The 5.7.1 error often signals a policy violation or unusual sending patterns.
- Sending Practices: Reviewing and correcting email sending practices is crucial for resolving the issue.
- Security Issues: The 5.7.1 error indicates issues of a security nature.
Key considerations
- RFC Compliance: Ensure all email headers comply with RFC 5322 specifications to avoid rejections.
- Header Formatting: Pay close attention to header formatting, avoiding any duplication of standard headers.
- Sending Libraries: Utilize proper email sending libraries or services to handle header formatting automatically.
- Friendly From: Avoid using special characters in the 'friendly from' field, as these can cause issues.
- Spam Content: Review email content and remove any spam-like characteristics.
Marketer view
Email marketer from Reddit shares that using a proper email sending library or service usually prevents duplicate header issues because they handle header formatting automatically. The user also highlights that manual construction of email headers is prone to errors.
16 Jun 2023 - Reddit
Marketer view
Marketer from Email Geeks explains that the error indicates duplicate headers, which are not permitted by RFC5322, and offers to help further if the headers are posted.
6 Mar 2022 - Email Geeks
What the experts say
3 expert opinions
The 5.7.1 delivery not authorized error in Gmail, specifically due to duplicate headers, is caused by Gmail's stricter enforcement of RFC 5322. A duplicate 'Message-ID' header can cause this issue. The bounces indicate non-compliance with RFC 5322. Resolving it involves correcting invalid, malformed, or duplicated SMTP header fields.
Key opinions
- RFC 5322 Enforcement: Gmail is enforcing RFC 5322 compliance more strictly, leading to bounces for non-compliant messages.
- Duplicate Message-ID: A duplicate 'Message-ID' header can specifically trigger the 5.7.1 error.
- SMTP Errors: A 5.7.1 error code signals SMTP errors related to invalid, malformed, or duplicated header fields.
Key considerations
- Header Validation: Validate email headers to ensure compliance with RFC 5322 specifications.
- Message-ID Uniqueness: Ensure that the 'Message-ID' header is unique for each email sent.
- SMTP Field Correction: Identify and correct any invalid, malformed, or duplicated header fields in SMTP.
Expert view
Expert from Spam Resource explains that Gmail is enforcing RFC 5322 more strictly, causing bounces due to issues like duplicate headers. The bounces indicate 'Our system has detected that this message is not RFC 5322 compliant' and suggest reviewing the specifications.
1 Jan 2022 - Spam Resource
Expert view
Expert from Word to the Wise reports that getting a Gmail 5.7.1 code is an indicator to look at SMTP errors. This means you must correct invalid, malformed or duplicated SMTP header fields.
13 Apr 2023 - Word to the Wise
What the documentation says
3 technical articles
The 5.7.1 'Delivery not authorized' error in Gmail, caused by duplicate headers, stems from violating email standards. RFC 5322 specifies that headers like 'To', 'From', 'Subject', and 'Date' should appear only once. Duplication leads to rejection. The 5.7.1 SMTP error signifies that the recipient server's policies are preventing delivery, potentially triggered by malformed headers.
Key findings
- RFC 5322 Violation: Duplicate headers violate RFC 5322, which dictates single occurrences for key headers.
- Delivery Not Authorized: The 5.7.1 error explicitly means 'Delivery not authorized, message refused' by the recipient server.
- Policy Trigger: Malformed headers can trigger the recipient server's policies, preventing delivery.
Key considerations
- Header Uniqueness: Ensure headers like 'To', 'From', 'Subject', and 'Date' appear only once in each email.
- Policy Compliance: Understand and adhere to recipient server policies to avoid delivery refusal.
- Header Validation: Thoroughly validate email headers for correct formatting to prevent triggering server-side policies.
Technical article
Documentation from Microsoft says that to ensure messages are correctly routed and delivered, it is important to avoid headers such as 'To', 'From', 'Subject', and 'Date' being duplicated. Servers reject messages because this violates standards.
28 Jan 2024 - Microsoft
Technical article
Documentation from RFC Editor specifies that certain headers like 'To', 'From', 'Subject', and 'Date' should appear only once in a message. Duplicate headers violate this specification, leading to potential rejection by email servers.
20 Aug 2021 - RFC Editor
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