Overview

MIME Overview Part I: A brief overview of the MIME specification

What is MIME (Multipurpose Internet Mail Extensions)?

Email has become an important, if not critical, part of communication on the internet. When RFC822 was published, email was meant as a simple means of exchanging text messages. At that time there wasn’t a need for attachments, multi-part emails, formatted emails, different rich clients, embedded images, embedded sounds etc. To provide these rich features, a new standard was created, that didn’t break RFC822.

Although a Mime message is considered to have parts, and part can have other parts, a Mime message is still one textual message. A properly formatted Mime (email) message can be opened in notepad, or any text editor. Each part is separated by boundaries.

A graphical representation of a Mime (Email) Message can be found below. In this drawing, the message contains headers, and two Mime parts; Part 1 and Part 2. Part 2, actually consists of two more mime parts; Part 2a, and Part 2b. This demonstrates that each Mime part can have additional children parts.




As an example, here is the text of a Mime message that contains a text and html part, along with some attachments. This mime message actually consists of 6 Mime Parts (as parsed by aspNetMime). Each of these parts are labeled as Mime Index n. Where 'n' is the index number.  The text in red describes the Mime message, but is not actually part of the message.  To see this message in its entirety, as a text message, click here.
 

Mime Index 0 
The Mime (Email) Message