2.2.8.10 PidTagSubject Property
Type: PtypString ([MS-OXCDATA] section 2.11.1)
The PidTagSubject property ([MS-OXPROPS] section 2.1034) SHOULD<30> be set to "Conv.Action: " followed by the value of the PidTagNormalizedSubject property (section 2.2.9.2) of an E-mail object in the conversation. This correlates the FAI message to the E-mail objects in the conversation.