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: https://www.iana.org/assignments/sasl-mechanisms/sasl-mechanisms.xhtml
- 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
- RFC 3501 INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1
IMAP extensions
- RFC 2595
STARTTLS
Using TLS with IMAP, POP3 and ACAP