==Implementations====Related Requests For Comments==* RFC 1123 – Requirements for Internet Hosts—Application and Support (STD 3)* RFC 1870 – SMTP Service Extension for Message Size Declaration (оbsoletes: RFC 1653)* RFC 2505 – Anti-Spam Recommendations for SMTP MTAs (BCP 30)* RFC 2920 – SMTP Service Extension for Command Pipelining (STD 60)* RFC 3030 – SMTP Service Extensions for Transmission of Large and Binary MIME Messages* RFC 3207 – SMTP Service Extension for Secure SMTP over Transport Layer Security (obsoletes RFC 2487)* RFC 3461 – SMTP Service Extension for Delivery Status Notifications (obsoletes RFC 1891)* RFC 3463 – Enhanced Status Codes for SMTP (obsoletes RFC 1893, updated by RFC 5248)* RFC 3464 – An Extensible Message Format for Delivery Status Notifications (obsoletes RFC 1894)* RFC 3798 – Message Disposition Notification (updates RFC 3461)* RFC 3834 – Recommendations for Automatic Responses to Electronic Mail* RFC 4952 – Overview and Framework for Internationalized E-mail (updated by RFC 5336)* RFC 4954 – SMTP Service Extension for Authentication (obsoletes RFC 2554, updates RFC 3463, updated by RFC 5248)* RFC 5068 – E-mail Submission Operations: Access and Accountability Requirements (BCP 134)* RFC 5248 - A Registry for SMTP Enhanced Mail System Status Codes (BCP 138) (updates RFC 3463)* RFC 5321 – The Simple Mail Transfer Protocol (obsoletes RFC 821 aka STD 10, RFC 974, RFC 1869, RFC 2821, updates RFC 1123)* RFC 5322 – Internet Message Format (obsoletes RFC 822 aka STD 11, and RFC 2822)* RFC 5504 – Downgrading Mechanism for Email Address Internationalization* RFC 6409 – Message Submission for Mail (STD 72) (obsoletes RFC 4409, RFC 2476)* RFC 6522 – The Multipart/Report Content Type for the Reporting of Mail System Administrative Messages (obsoletes RFC 3462, and in turn RFC 1892)* RFC 6531 – SMTP Extension for Internationalized Email Addresses (updates RFC 2821, RFC 2822, RFC 4952, and RFC 5336)==See also==*Bounce address*Email encryption*Ident*POP before SMTP / SMTP after POP*Sender Policy Framework (SPF)*Variable envelope return path*Dkim==Notes====References====External links==* Email Address Internationalization IETF Working Group
Если же сервер поддерживает ESMTP, то кроме приветствия он сообщит список поддерживаемых расширений протокола SMTP, например:== Стандарты RFC ==* RFC 1870 SMTP Service Extension for Message Size Declaration (заменяет RFC 1653)* RFC 2034 SMTP Service Extension for Returning Enhanced Error Codes* RFC 2505 Anti-Spam Recommendations for SMTP MTAs (BCP 30)* RFC 4954 SMTP Service Extension for Authentication (заменяет RFC 2554)* RFC 2822 Internet Message Format (заменяет RFC 822 aka STD 11)* RFC 2920 SMTP Service Extension for Command Pipelining (STD 60)* RFC 3030 SMTP Service Extensions for Transmission of Large and Binary MIME Messages* RFC 3207 SMTP Service Extension for Secure SMTP over Transport Layer Security (заменяет RFC 2487)* RFC 3461 SMTP Service Extension for Delivery Status Notifications (заменяет RFC 1891)* RFC 3462 The Multipart/Report Content Type for the Reporting of Mail System Administrative Messages (заменяет RFC 1892)* RFC 3463 Enhanced Status Codes for SMTP (заменяет RFC 1893)* RFC 3464 An Extensible Message Format for Delivery Status Notifications (заменяет RFC 1894)* RFC 3552 Guidelines for Writing RFC Text on Security Considerations* RFC 3834 Recommendations for Automatic Responses to Electronic Mail* RFC 4409 Message Submission for Mail (заменяет RFC 2476)* RFC 5321 Simple Mail Transfer Protocol (заменяет RFC 821 aka STD 10, RFC 974, RFC 1869, RFC 2821)* RFC 5336 SMTP Extension for Internationalized Email Addresses* Перевод RFC 2505 — Рекомендации по предотвращению спама для SMTP MTA* Перевод RFC 2554 — Расширение сервиса SMTP для аутентификации* Перевод RFC 5321 — Простой протокол передачи электронной почты (SMTP)* LMTP — производный от SMTP протокол, ориентированный на работу без очереди сообщений.