220.127.116.11.5 Embedded Message Attachments
This section describes the generation of MIME entities that correspond to embedded message attachments. An Attachment object is considered by MIME writers to be an embedded message attachment if the value of its PidTagAttachMethod property ([MS-OXCMSG] section 18.104.22.168) is 0x00000005. MIME writers SHOULD generate a MIME entity with the Content-Type header (2) set to "message/rfc822" (without parameters being generated). No other MIME headers SHOULD be generated. Instead, MIME writers SHOULD use properties of the embedded message to generate a pure MIME message representation of this message, exactly as specified for ordinary messages, and use this data as the content of the MIME entity whose Content-Type header value is "message/rfc822". This MIME representation SHOULD be generated exactly as specified for ordinary messages, with the following exception: when writing MIME message headers by using PS_INTERNET_HEADERS properties, as specified in section 22.214.171.124.4, properties whose names begin with "X-MS-Exchange-Organization-" or "X-MS-Exchange-Forest-" SHOULD NOT be excluded from MIME generation (as they are for ordinary messages).