SMTP (RFC 5321)
- Category
- Web and networking protocols
- Docs outline
- 8 sections
Official docs outline
rfc-editor.org- Basic structure
Client/server model, mail objects, envelope and relay roles.
- Session initiation and mail transactions
EHLO, MAIL FROM, RCPT TO, DATA and QUIT procedure.
- Command specifications
SMTP verbs and their syntax.
- Reply codes
2xx/3xx/4xx/5xx reply code meaning and enhanced status.
- Address resolution and MX
Locating the target host using MX and A/AAAA records.
- Message format (RFC 5322)
Header fields, addresses and message structure.
- STARTTLS extension
Upgrading an SMTP connection to TLS.
- Message submission
Submission service on port 587 and authentication.
Each section links to the official page. Titles and summaries by Extra Credit; the docs belong to their authors.