2.2.3.2.15 Content Class

To set the value of the PidNameContentClass property ([MS-OXCMSG] section 2.2.1.48), clients SHOULD<119> write the value to a Content-Class header.

MIME readers copy the value of a Content-Class header to the value of the PidNameContentClass property.

MIME readers SHOULD<120> also set the value of the PidTagMessageClass property ([MS-OXCMSG] section 2.2.1.3) for certain Content-Class header values as specified in the following table, but only if the value of the PidTagMessageClass property would otherwise be set to "IPM.Note". MIME readers SHOULD verify that the content of the MIME message conforms to the additional requirements specified in the corresponding sections listed in the "Additional requirements" column. If the MIME message does not conform to the additional requirements, the PidTagMessageClass property SHOULD be set to "IPM.Note".

Additionally, if the Content-Class header value begins with "InfoPath.", MIME readers SHOULD extract a substring from the header value beginning immediately after the prefix and ending at the end of the header value. If this string contains a period character (U+002E), and the first occurrence of this character is not the last one in the string, this string SHOULD be further separated into two substrings. The delimiting period is not included into either one of the substrings.

The first substring SHOULD be additionally checked to match the string format of a GUID string, as specified in [MS-DTYP]. If this check succeeds, the second substring SHOULD be saved as a value of the PidLidInfoPathFormName property ([MS-OXCMSG] section 2.2.1.27). In addition, the first substring SHOULD be appended to "IPM.InfoPathForm." and written to the value of the PidTagMessageClass property.

If a message that is being processed by a MIME reader is clear signed or opaque signed, as specified in [MS-OXOSMIME], the appropriate suffix (".SMIME.MultipartSigned" or ".SMIME") SHOULD be appended to the value of the PidTagMessageClass property.