Microsoft KB Archive/323226

= XCON: A Description of the Multipart/Mixed Internet Message Format =

Article ID: 323226

Article Last Modified on 10/27/2006

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APPLIES TO


 * Microsoft Exchange Server 2000 Service Pack 1
 * Microsoft Exchange 2000 Server Service Pack 2
 * Microsoft Exchange Server 5.5 Service Pack 4

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This article was previously published under Q323226



SUMMARY
An e-mail message sent from one of the versions of Exchange Server that are listed at the beginning of this article may appear as a multipart/mixed Multipurpose Internet Message Extensions (MIME) message with separate body parts that are delineated by a border.



MORE INFORMATION
A multipart/mixed MIME message is composed of a mix of different data types. Each body part is delineated by a boundary. The boundary parameter is a text string used to delineate one part of the message body from another. All boundaries start with two hyphens (--). The final boundary also concludes with two hyphens (--). The boundary can be made up of any ASCII character except for a space, a control character, or special characters.

When Exchange Server sends MIME messages, the content-type depends on whether there are attachments to the message, and on the formatting of the message text. If there are attachments, the content-type is multipart/mixed. In this case, the message text and each attachment become a separate part of the message content, each with its own content-type. If there are no attachments, the content-type of the message is Text/Plain, and the message body is made up of only one part.

A multipart/mixed MIME message header of a message sent with a Microsoft Word attachment may appear similar to the following:

Content-type: multipart/mixed;

boundary=&quot;Boundary_ &quot;

--Boundary_

content-Type: text/plain;

charset=iso-8859-1

Content-transfer-encoding: 7BIT

--Boundary_

Content-type: application/msword;

name=&quot;message.doc&quot;

Content-Transfer-Encoding: base64

Messages that are composed by MIME clients as a multipart/mixed MIME message without a &quot;name&quot; parameter for the &quot;content-type&quot; or an optional &quot;filename&quot; parameter for the &quot;content-disposition&quot; header may not be rendered correctly when received by Exchange.

Keywords: kbinfo KB323226

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