How to troubleshoot email delivery issues related to RFC compliance errors?

Summary

Troubleshooting RFC compliance errors in email delivery involves a multi-faceted approach encompassing technical standards, DNS configurations, header and content analysis, and authentication protocols. Experts emphasize the importance of RFC compliance for email system interoperability, noting that the sender is primarily responsible for troubleshooting. DNS issues are a common cause, requiring careful verification of SPF, DKIM, and DMARC records. Analyzing message headers is crucial for tracing email paths and identifying violations, while checking for correct formatting of `Date:` headers, line breaks (CRLF), and valid MIME types is also important. Additional steps include using RFC validators, reviewing raw message content for invalid characters, encoding headers appropriately, and ensuring no extra or missing headers are present. Specific issues like duplicated sender addresses or special characters in the 'friendly from' field can also lead to errors. Finally, documentation from IETF and Mailhardener provide essential guidance on SMTP, IMF, and common RFC errors.

Key findings

  • RFC Compliance is Essential: RFC compliance is fundamental for email system interoperability; deviations result in delivery issues.
  • Sender Responsibility: Senders are primarily responsible for diagnosing and resolving RFC compliance errors.
  • DNS Configuration: DNS configuration problems (SPF, DKIM, DMARC) are a common root cause of RFC errors.
  • Header Analysis is Key: Examining message headers helps trace email paths and pinpoint RFC violations.
  • Content and Formatting: Correct formatting of Date headers, line breaks (CRLF), and MIME types is crucial.
  • Invalid Characters: Invalid or non-ASCII characters in headers can trigger errors.
  • Friendly From Issues: Special characters or duplicated sender addresses in the 'friendly from' field cause problems.
  • Canonical References: RFC5321 and RFC5322 are primary references for understanding RFC specifications.

Key considerations

  • Prioritize Standards Adherence: Always prioritize adherence to RFC standards to ensure consistent email delivery.
  • Proactive Approach: Adopt a proactive approach to troubleshooting, not relying on ISPs for resolution.
  • Regular DNS Verification: Regularly verify DNS records (SPF, DKIM, DMARC) to prevent DNS-related issues.
  • Thorough Header Analysis: Thoroughly analyze email headers to trace message paths and identify errors.
  • Content Scrutiny: Scrutinize raw message content for invalid characters and formatting issues.
  • Validation Tools: Utilize RFC validators and header analysis tools to aid in troubleshooting.
  • Address Specific Issues: Pay attention to platform-specific issues (e.g., Yahoo's 'friendly from' sensitivity).
  • Consult RFC Documentation: Consult RFC documentation (RFC5321, RFC5322) for a deeper understanding of the standards.

What email marketers say
11Marketer opinions

Troubleshooting RFC compliance errors in email delivery involves several key areas. These include examining message headers for path tracing, validating SPF and DKIM records for authentication, ensuring correct formatting of the `Date:` header and line breaks (CRLF), using RFC validators, correctly defining MIME types, checking for invalid characters in headers (and encoding if necessary), reviewing raw message content, and ensuring no extra or missing headers are present. Specific issues such as special characters or duplicated sender addresses in the 'friendly from' field can also cause problems.

Key opinions

  • Header Analysis: Examining message headers is crucial for tracing the email's path and identifying where RFC violations occur.
  • Authentication Records: Incorrect or missing SPF and DKIM records can lead to RFC compliance issues due to failed sender authentication.
  • Date Header Format: A valid and properly formatted `Date:` header is essential; many systems reject messages lacking this.
  • Line Breaks: Ensure proper line breaks (CRLF) are used throughout the email body and headers.
  • RFC Validation: RFC validators can be used to check compliance with RFC specifications.
  • MIME Types: Incorrectly defined MIME types can lead to delivery errors.
  • Invalid Characters: Invalid or non-ASCII characters in headers can trigger RFC errors; use encoding if necessary.
  • Raw Content Review: Reviewing raw message content can reveal hidden formatting issues or control characters.
  • Header Integrity: Ensure all headers are present and that there are no extra headers.
  • Friendly From Field: Special characters and duplicated sender addresses in the 'friendly from' field can cause compliance issues.

Key considerations

  • Header Examination: Always start by thoroughly examining the email headers to pinpoint the source of the RFC violation.
  • Authentication Setup: Regularly validate SPF, DKIM, and DMARC records to ensure proper email authentication.
  • Format Compliance: Pay close attention to formatting details such as the `Date:` header and line breaks.
  • Content Review: Review raw message content for hidden issues like invalid characters or formatting errors.
  • Tools Utilization: Use RFC validators and header analysis tools to aid in troubleshooting.
  • Specific Platforms: Be aware of platform-specific issues, like Yahoo's sensitivity to certain characters in the friendly from address.
Marketer view

Email marketer from Gmass shares the use of using an RFC validator. This type of tool will check to ensure you're abiding by the proper specifications.

January 2023 - Gmass
Marketer view

Email marketer from Reddit explains that incorrect or missing SPF and DKIM records can lead to RFC compliance issues, as they are essential for authenticating the sender. He advises using online tools to validate these records and ensure they are properly configured.

March 2023 - Reddit
Marketer view

Email marketer from Postmastery explains that ensuring a valid and properly formatted `Date:` header is present is essential for RFC compliance. Many systems reject messages without it, or with a date that is significantly in the future or past.

July 2021 - Postmastery
Marketer view

Email marketer from SocketLabs explains that ensuring proper line breaks (CRLF) are used throughout the email body and headers is essential. Some systems are strict about this and will reject messages that use only LF or CR.

September 2024 - SocketLabs
Marketer view

Email marketer from EmailDudes Forum shares that invalid or non-ASCII characters in the 'From,' 'To,' or 'Subject' headers can trigger RFC compliance errors. They suggest encoding these headers using quoted-printable or base64 encoding.

October 2022 - EmailDudes Forum
Marketer view

Marketer from Email Geeks explains the solution to the RFC compliance error was that the client was adding their sender address into the friendly from, thus duplicating the sender.

November 2024 - Email Geeks
Marketer view

Email marketer from Stack Overflow explains that examining the full message headers is crucial. Look for 'Received:' headers to trace the path of the email and identify where the RFC violation might have occurred. Tools like messageheader.com can help analyze the headers.

January 2024 - Stack Overflow
Marketer view

Email marketer from Reddit shares to double check all headers. Ensure there are no extra headers or missing ones.

October 2023 - Reddit
Marketer view

Email marketer from Mailosaur recommends reviewing the raw message content to identify any hidden formatting issues or control characters that might be causing problems.

November 2023 - Mailosaur
Marketer view

Marketer from Email Geeks suggests checking for special characters in the friendly from address, as certain characters can cause RFC compliance issues with Yahoo.

February 2022 - Email Geeks
Marketer view

Email marketer from Mailjet shares to ensure all MIME types are defined correctly. Defining these incorrectly can lead to errors.

July 2022 - Mailjet

What the experts say
5Expert opinions

Troubleshooting RFC compliance errors in email delivery requires a comprehensive approach focusing on adherence to standards and proactive problem-solving. Experts emphasize that RFC compliance is fundamental for interoperability, and deviations can lead to unpredictable delivery issues. DNS configuration problems are often a root cause, making proper setup and verification of DNS records (SPF, DKIM, DMARC) essential. A thorough checklist includes examining DNS issues, authentication record correctness, line lengths, CR/LF termination, TLS negotiation, MIME type correctness, high ASCII encoding, and the presence of a DATE header. Furthermore, the sender is primarily responsible for troubleshooting these errors and should consult RFC5321 and RFC5322 for canonical guidance.

Key opinions

  • RFC Compliance is Key: RFC compliance is essential for email system interoperability, and deviations can cause unpredictable delivery problems.
  • Sender Responsibility: The sender bears the primary responsibility for troubleshooting RFC compliance errors.
  • DNS Configuration: DNS configuration problems are a frequent cause of RFC compliance errors, emphasizing the importance of verifying DNS records.
  • Comprehensive Checklist: A comprehensive checklist includes examining various elements like DNS, authentication records, line lengths, and header information.
  • Canonical References: RFC5321 and RFC5322 serve as the canonical references for understanding RFC compliance.

Key considerations

  • Adherence to Standards: Prioritize adherence to RFC standards to ensure consistent email delivery.
  • Proactive Troubleshooting: Take a proactive approach to troubleshooting, rather than relying on ISPs to resolve compliance issues.
  • DNS Verification: Routinely verify DNS records (SPF, DKIM, DMARC) to prevent DNS-related delivery failures.
  • Detailed Examination: Conduct a detailed examination of various email elements, including headers, content, and encoding, to identify potential issues.
  • Resource Utilization: Consult RFC5321 and RFC5322 to gain a deeper understanding of the standards and requirements for RFC compliance.
Expert view

Expert from Spam Resource explains that RFC compliance is fundamental for interoperability in email systems. Deviations from RFC standards can lead to unpredictable delivery issues and make troubleshooting difficult, emphasizing the need to adhere to established protocols.

May 2022 - Spam Resource
Expert view

Expert from Email Geeks stresses that when encountering RFC compliance errors, it's the sender's responsibility to troubleshoot the issue, rather than expecting the ISP to do so.

January 2025 - Email Geeks
Expert view

Expert from Email Geeks identifies RFC5321 and RFC5322 as the canonical references for RFC compliance.

December 2023 - Email Geeks
Expert view

Expert from Word to the Wise discusses how DNS configuration problems often lead to email delivery failures that manifest as RFC compliance errors. She recommends verifying that all DNS records (SPF, DKIM, DMARC) are correctly set up and propagated to prevent issues.

July 2023 - Word to the Wise
Expert view

Expert from Email Geeks provides a comprehensive list of things to check when encountering RFC compliance errors, including DNS issues, DKIM/SPF/DMARC correctness, bare IP addresses in links, line lengths, CR/LF termination, TLS negotiation, MIME type correctness, high ASCII encoding, and the presence of a DATE header. She also suggests contacting postmaster@ for assistance.

December 2021 - Email Geeks

What the documentation says
4Technical articles

Troubleshooting RFC compliance errors involves understanding the fundamental protocols and message formats governing email. SMTP, as defined by IETF, dictates message format, transmission protocols, and error handling. The Internet Message Format (IMF), also specified by IETF, governs email header syntax and body structure semantics. Common errors to watch out for, as highlighted by Mailhardener, include missing or invalid Date headers, incorrect line endings (LF instead of CRLF), and exceeding line length limits. PowerDMARC provides insights into the different types of RFCs and how to implement and troubleshoot them.

Key findings

  • SMTP Definition: SMTP (defined by IETF) dictates the message format, transmission protocols, and error handling for email.
  • IMF Specification: IMF (specified by IETF) governs the syntax and semantics of email headers and body structures.
  • Common RFC Errors: Common RFC errors include missing/invalid Date headers, incorrect line endings (LF instead of CRLF), and exceeding line length limits.
  • RFC Types: Different types of RFC exist, each with distinct definitions and troubleshooting methods.

Key considerations

  • Protocol Understanding: Develop a strong understanding of SMTP and IMF to effectively troubleshoot RFC compliance issues.
  • Header and Body Scrutiny: Carefully examine email headers and body structures to ensure compliance with IMF specifications.
  • Common Error Checks: Prioritize checking for missing/invalid Date headers, line ending errors, and line length limits when troubleshooting.
  • RFC-Specific Troubleshooting: Understand the specific RFCs relevant to your email system and how to implement/troubleshoot them.
Technical article

Documentation from ietf.org defines the Simple Mail Transfer Protocol (SMTP), outlining message format, transmission protocols, and error handling, crucial for ensuring RFC compliance.

March 2021 - ietf.org
Technical article

Documentation from PowerDMARC lists different types of RFC, and how they are different. Provides definitions for each and ways to implement or troubleshoot.

April 2023 - PowerDMARC
Technical article

Documentation from ietf.org specifies the Internet Message Format (IMF), which governs the syntax and semantics of email headers and body structures, vital for understanding and troubleshooting RFC compliance errors.

August 2024 - ietf.org
Technical article

Documentation from Mailhardener highlights common RFC errors such as missing or invalid Date headers, incorrect line endings (using LF instead of CRLF), and exceeding line length limits. It advises checking these elements first when troubleshooting.

June 2023 - Mailhardener