What is the RFC that defines email?

Email standards are primarily defined by RFC 5321 (for SMTP) and RFC 5322 (for message format and headers). These documents describe how email should be structured, transmitted, and interpreted.

RFC stands for Request for Comments, a series of technical documents published by the Internet Engineering Task Force (IETF) since 1969\. Despite the modest name, RFCs are the authoritative specifications that govern how the internet works. RFC 822 (1982) was the original email standard, later updated to RFC 2822 (2001), and finally RFC 5322 (2008) which we use today.

Beyond these core documents, there are additional related protocols that make email function securely and reliably. MIME is defined in RFC 2045-2049, SPF in RFC 7208, DKIM in RFC 6376, and DMARC in RFC 7489.

Think of SMTP as the fleet that delivers letters from port to port, while IMAP and POP3 are the smaller boats bringing the mail ashore. SSL/TLS and STARTTLS secure the routes between ports, creating encrypted tunnels to protect cargo from pirates.

They are the maritime laws of email, guidelines that ensure all vessels communicate using the same rules at sea while enforcing security and trust in modern waters.