2.1.3.2.1 Message Class

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When generating a TNEF message, MIME writers copy the value of the PidTagMessageClass property ([MS-OXCMSG] section 2.2.1.3) to the attMsgProps attribute, as specified in [MS-OXTNEF] section 2.1.3.3.21, in the TNEF body part. In addition, MIME writers SHOULD map the value of the PidTagMessageClass property to the attMessageClass attribute, as specified in [MS-OXTNEF] section 2.1.3.3.5.

When generating pure MIME messages, the value of the PidTagMessageClass property SHOULD NOT be copied to the MIME messages. Instead, its value is reflected in the structure of the MIME message, as specified in the following table. The MIME structure is indicated by listing the value of the Content-Type header, indented according to how the MIME entities are nested.

PidTagMessageClass property value

MIME structure

"IPM.Note.SMIME.MultipartSigned", or begins with "IPM.InfoPathForm." and ends with ".SMIME.MultipartSigned"

Multipart/signed, as specified in [RFC5751] and [MS-OXOSMIME].

"IPM.Note.SMIME", or begins with "IPM.InfoPathForm." and ends with ".SMIME"

Application/pkcs7-MIME, as specified in [RFC5751] and [MS-OXOSMIME].

"REPORT.IPM.Note.DR" or "REPORT.IPM.Note.NDR" (other values MAY be substituted for "IPM.Note")

As specified in [RFC3464]:

"multipart/report"

"text/HTML"

"message/delivery-status"

<original message structure>

For details, see section 2.1.3.6.1.

"REPORT.IPM.Note.IPNRN" or "REPORT.IPM.Note.IPNNRN" (other values MAY be substituted for "IPM.Note")

As specified in [RFC3798]:

"multipart/report"

"text/HTML"

Message/disposition-notification

For details, see section 2.1.3.6.2.

Equals "IPM.Appointment" or begins with "IPM.Appointment."

"text/calendar", as specified in [RFC2445] and [MS-OXCICAL].<22>

Begins with "IPM.Schedule.Meeting."

Content mapped to "text/calendar", as specified in [RFC2445] and [MS-OXCICAL].

Top-level message structure is "multipart/alternative" or "multipart/mixed", depending on the presence and type of message body and attachments. For details, see section 2.1.3.3.

"IPM.Note" or any other value

"text/plain", "text/HTML", "multipart/alternative", "multipart/related", as specified in [RFC2387], or "multipart/mixed", depending on the presence and type of message body and attachments. For details, see section 2.1.3.3.