What is the Email Content-Type Header (ie MIME)?


Content-type is a email headers that defines:

  • the type of the body
  • or the type of one of the body parts


Where the first parameter is the media type (mime)

Single part

  • HTML
Content-Type: text/html; charset="UTF-8"
  • Plain Text
Content-Type: text/plain; charset="UTF-8"
Content-Type: message/rfc822
  • Delivery Status
Content-Type: message/delivery-status
  • Attached Image
Content-Type: image/png; name="icon.png"
Content-Disposition: attachment; filename="icon.png"
Content-Transfer-Encoding: base64
Content-ID: <icon.png>


Multipart media type means that the body is composed of multiple single part

  • Multipart alternative. The parts are alternative to each other and represent the same content. The client can show one or the other part. Normally used to show a text if the client does not support HTML rendering.
Content-Type: multipart/alternative; boundary="0000000000008c12850607c40b30"
  • Multipart related. The parts are related but do not represent the same content.
Content-Type: multipart/related; boundary="0000000000008c12780607c40b2f"
  • Multipart report (in case of a bounce)
Content-Type: multipart/report; boundary="0000000000008c07b00607c40b27"; report-type=delivery-status


It has the same functionality and syntax than the HTTP content type header


Content-Type: mediaType; parameter1=value1; parameter2=value2


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