RFC 5322 is a standard that defines the format of email messages. This includes the syntax of email addresses, the structure of the headers, and the types of content that can be included in the body of an email message. So whether you use Gmail in your web browser, or maybe you use a desktop application like thunderbird, you can receive and send emails to anybody and all email clients should display the email the same.

The standard was published by the IETF (which stands for Internet Engineering Task Force). It is a group responsible for the development of many of the protocols that are used on the internet today. The goal of the standard is to provide a consistent and interoperable format for email messages so that they can be exchanged between different email systems and clients all over the world.

What are some rules set by RFC 5322?

For example, it defines the syntax of email addresses, which includes the local part (the part of the address that appears before the @ symbol) and the domain name (the part after @). It also defines the structure of the message headers, which are used to convey information about the sender, recipient, subject, and other metadata about the message.

Additionally, the standard defines the various types of content that can be included in the body of an email message, such as text, images, and other multimedia content. It also defines the rules for how this content can be encoded and formatted so that email clients can properly display it.