RFC5321
RFC5321
- April 21, 2021
- Posted by: Nicola Selenu

This document is a specification of the basic protocol for Internet electronic mail transport. It consolidates, updates, and clarifies several previous documents, making all or parts of most of them obsolete. It covers the SMTP extension mechanisms and best practices for the contemporary Internet, but does not provide details about particular extensions. Although SMTP was designed as a mail transport and delivery protocol, this specification also contains information that is important to its use as a “mail submission” protocol for “split-UA” (User Agent) mail reading systems and mobile environments.
- RFC5321 FULL TEXT
- How to set up your SenderID records if you are outsourcing some, or all, of your email
- How to set up your DKIM records if you are outsourcing some, or all, of your email and still build your reputation
- How to set up your SPF records if you are outsourcing some, or all, of your email
- How to set up your DKIM records if you are outsourcing some, or all, of your email
Author:Nicola Selenu
Email Service Providers Handbook
The most comprehensive “Handbook of Email Service Providers“!
SPAMASSASSIN RULES
All SpamAssassin rules in one place, EXPLAINED!
SMTP COMMANDS
& REPLY CODES
All SMTP/ESMTP commands and reply codes in one place, EXPLAINED!
Free DNS Tool
Check the DNS records of your domain with our free DNS tool.
Deliverability Glossary
The most comprehensive Email Deliverability and Marketing Glossary!
- RFC5321 FULL TEXT
- How to set up your SenderID records if you are outsourcing some, or all, of your email
- How to set up your DKIM records if you are outsourcing some, or all, of your email and still build your reputation
- How to set up your SPF records if you are outsourcing some, or all, of your email
- How to set up your DKIM records if you are outsourcing some, or all, of your email
RFC5321
Simple Mail Transfer Protocol
This document is a specification of the basic protocol for Internet electronic mail transport. It consolidates, updates, and clarifies several previous documents, making all or parts of most of them obsolete. It covers the SMTP extension mechanisms and best practices for the contemporary Internet, but does not provide details about particular extensions. Although SMTP was designed as a mail transport and delivery protocol, this specification also contains information that is important to its use as a “mail submission” protocol for “split-UA” (User Agent) mail reading systems and mobile environments.
« Back to Glossary IndexAuthor:Nicola Selenu
Email Service Providers Handbook
The most comprehensive “Handbook of Email Service Providers“!
SPAMASSASSIN RULES
All SpamAssassin rules in one place, EXPLAINED!
SMTP COMMANDS
& REPLY CODES
All SMTP/ESMTP commands and reply codes in one place, EXPLAINED!
Free DNS Tool
Check the DNS records of your domain with our free DNS tool.
Deliverability Glossary
The most comprehensive Email Deliverability and Marketing Glossary!
« Back to Glossary Index