= Multipurpose Internet Mail Extensions =

'''Multipurpose Internet Mail Extensions''' ('''MIME''') is a standard for handling emails that may not exclsively contain printable ASCII characters.

<<TableOfContents>>

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== Structure ==



=== Header ===

A MIME message begins with:

{{{
MIME-Version: 1.0
}}}

In theory there could be breaking changes in a different version of MIME, but the standard does not cover how a different version should be handled by message agent that do not support it. As such, MIME is stuck at version 1.0 permanently.



=== Content Types ===

A MIME message continues with a line like:

{{{
Content-Type: multipart/mixed
}}}

A MIME message containing just ASCII text could use a content type of `text/plain`. But in practice, most MIME messages contain at least an HTML formatted message (`text/html`) and a test message (`text/plain`). In this case, the message has a type of `multipart/mixed` and each component of the message will have a new content type.

In the case of a multipart message, the content type looks like:

{{{
Content-Type: multipart/alternative;    boundary="_000_CY4PR11MB1894D7
	22452F4E01EBDDC61E85790CY4PR11MB1894namp_"
}}}

The message should be scanned for the boundary to identify the separable components.

A character set may also be specified like

{{{
Content-Type: text/plain; charset="utf-8"
}}}

Note that the character set values are not well specified.



=== Content Transfer Encoding ===

A MIME message or component may continue with a specification of the character encoding. This generally is only seen in use with [[Email/Base64|base64]]...


{{{
Content-Type: application/octet-stream
Content-Transfer-Encoding: base64
}}}

...or [[Email/QuotedPrintable|quoted-printable]].

{{{
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
}}}

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== History ==



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