What is an RFC (Request for Comments)?
An RFC (Request for Comments) is a publication from the Internet Engineering Task Force (IETF) documenting technical specifications, protocols, procedures, and informational topics about the internet. Despite the humble name, RFCs are authoritative standards that define how internet systems work.
The RFC series began in 1969 and now includes thousands of documents covering everything from core protocols to operational guidelines. Each RFC has a number (like RFC 5321) and a status indicating its authority level.
For email, RFCs define SMTP message transfer, message format structure, authentication mechanisms, and related protocols. Understanding relevant RFCs helps troubleshoot problems and ensure compliance with technical requirements that affect deliverability.
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