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RFCs conformed

SMTP core

  • RFC 3463 Enhanced Mail System Status Codes
  • RFC 5321 Simple Mail Transfer Protocol
  • RFC 6409 Message Submission for Mail
  • RFC 8314 Cleartext Considered Obsolete: Use of Transport Layer Security (TLS) for Email Submission and Access

SMTP extensions

  • RFC 1870 SIZE SMTP Service Extension for Message Size Declaration
  • RFC 2034 ENHANCEDSTATUSCODES SMTP Service Extension for Returning Enhanced Error Codes
  • RFC 2920 PIPELINING SMTP Service Extension for Command Pipelining
  • RFC 3207 STARTTLS SMTP Service Extension for Secure SMTP over Transport Layer Security
  • RFC 4954 AUTH SMTP Service Extension for Authentication
  • RFC 6152 8BITMIME SMTP Service Extension for 8-bit MIME Transport
  • RFC 6531 SMTPUTF8 SMTP Extension for Internationalized Email

SASL mechanisms for AUTH extension

Available mechanisms list:

  • RFC 4616 PLAIN The PLAIN Simple Authentication and Security Layer (SASL) Mechanism

SMTP security

  • RFC 6376 DomainKeys Identified Mail (DKIM) Signatures
  • RFC 7208 Sender Policy Framework (SPF) for Authorizing Use of Domains in Email, Version 1
  • RFC 7489 Domain-based Message Authentication, Reporting, and Conformance (DMARC)

IMAP core


IMAP extensions

  • RFC 2595 STARTTLS Using TLS with IMAP, POP3 and ACAP