2.2.3.3.2.1 Selecting the Primary Message Text MIME Element

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When alternative text MIME elements are present and eligible for use as the message body, as specified in section 2.2.3.3.2, MIME readers SHOULD choose a MIME element to populate the message body text by using the following content types, in descending order of preference:

  • "text/HTML"

  • "text/enriched"

  • "text/plain"

  • "text/calendar" (but only if the METHOD property value of the "text/calendar" body part is PUBLISH, REQUEST, REPLY, or CANCEL)

If "text/HTML" is selected, MIME readers copy the MIME element body text to the value of the PidTagHtml property ([MS-OXCMSG] section 2.2.1.58.9), map the charset parameter of the MIME element's Content-Type header to a code page, and set the value of the PidTagInternetCodepage property ([MS-OXCMSG] section 2.2.1.58.6) to that code page. If the charset parameter is not present, MIME readers MAY use the value of a Content-Type META element in the HTML document but SHOULD verify its validity before using it.

If "text/plain" is selected, MIME readers convert the plain text to the UTF-16LE scheme and write the resulting text to the value of the PidTagBody property ([MS-OXCMSG] section 2.2.1.58.1). MIME readers SHOULD, in addition, map the value of the charset parameter of the MIME element's Content-Type header to a code page and set the value of the PidTagInternetCodepage property to that code page.

If "text/enriched" is selected, MIME readers convert the MIME element body text to either "text/plain", "text/HTML", or "text/RTF" and handle that as previously specified. The conversion of enriched text format to other formats is specified in Appendix B of [RFC1896].

If both "text/HTML" and "text/calendar" body parts are present and eligible for use as a message body, instead of writing text to the PidTagHtml property, MIME readers SHOULD convert the HTML text to RTF and write it to the value of the PidTagRtfCompressed property ([MS-OXCMSG] section 2.2.1.58.4). Alternatively, MIME readers can choose to use plain text from a "text/plain" body part or from data in the "text/calendar" body part, as specified in [MS-OXCICAL]. MIME readers MUST NOT set the PidTagHtml property on a calendar or meeting Message object.