2.2.1.58.7 PidTagBodyContentId Property
Type: PtypString ([MS-OXCDATA] section 2.11.1)
The PidTagBodyContentId property ([MS-OXPROPS] section 2.619) contains a GUID corresponding to the current message body.
This property corresponds to the Content-ID header. The relationship between this property and the Content-ID header is further specified in [MS-OXCMAIL] sections 2.1.3.4.2.3 and 2.2.3.2.24.