Table of Contents

What is the Mime (Multipurpose Internet Mail Extensions) ?

About

In the context of email, mime may have two different definitions:

Definitions

Encoding

The mime is just the text structure of an email message (known as mime message).

Example:

Delivered-To: [email protected]
Received: by 2002:a05:6504:519b:0:0:0:0 with SMTP id z27csp820130ltq;
Date: Fri, 12 Jun 2020 21:08:18 +0200
To: [email protected]
Subject: Without hosts dkim test !
User-Agent: Heirloom mailx 12.5 7/5/10
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Message-Id: <[email protected]>
From: [email protected] (root)
cc: [email protected]
bcc: [email protected]

This is the body of the email

The MIME is specified by the following RFCs if you want to get all details

Rfc Description
RFC2045 Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies
RFC2046 Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types (See also media type)
RFC2047 MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text

Media Type

mime is also used widely to refer to the media type (content-type) because this is where it comes from.

An email may be sent with multiformat (with multiple media types)

It's specified in the content-type header and defines the format of the email body

Content-Type: text/html; charset="utf-8"
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable