2.2.2.6 PidTagOriginalSenderAddressType Property
Type: PtypString ([MS-OXCDATA] section 2.11.1)
The PidTagOriginalSenderAddressType property ([MS-OXPROPS] section 2.833) is set on delivery report messages by using the value of the original message sender's PidTagSenderAddressType property (section 2.2.1.48), as specified by AddressType field of the RecipientRow structure ([MS-OXCDATA] section 2.8.3.2).