SMTP

RFC 5321 - Simple Mail Transfer Protocol

RFC 5321 is the IETF standard defining the Simple Mail Transfer Protocol. It specifies the client-server protocol used to transmit email across the internet, including the command set, response codes, session lifecycle, and extension mechanism (ESMTP). Published October 2008, it obsoletes RFC 2821.

GitHub

Other Resources

🔗
Specification
https://datatracker.ietf.org/doc/html/rfc5321
🔗
RFC Editor
https://www.rfc-editor.org/rfc/rfc5321.html
🔗
IETF Datatracker
https://datatracker.ietf.org/doc/rfc5321/
🔗
APIsJSON
https://raw.githubusercontent.com/api-evangelist/smtp/refs/heads/main/apis.yml

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API entry from apis.yml

apis.yml Raw ↑ 
aid: smtp:rfc5321
name: RFC 5321 - Simple Mail Transfer Protocol
description: RFC 5321 is the IETF standard defining the Simple Mail Transfer Protocol. It specifies the
  client-server protocol used to transmit email across the internet, including the command set, response
  codes, session lifecycle, and extension mechanism (ESMTP). Published October 2008, it obsoletes RFC
  2821.
humanURL: https://datatracker.ietf.org/doc/html/rfc5321
tags:
- SMTP
- RFC
- IETF
- Email Protocol
- Standards
properties:
- type: Specification
  url: https://datatracker.ietf.org/doc/html/rfc5321
- type: RFC Editor
  url: https://www.rfc-editor.org/rfc/rfc5321.html
- type: IETF Datatracker
  url: https://datatracker.ietf.org/doc/rfc5321/