2.2.1.51 PidTagSenderName Property
Type: PtypString ([MS-OXCDATA] section 2.11.1)
The PidTagSenderName property ([MS-OXPROPS] section 2.1005) contains the sending mailbox owner's display name, as specified by the DisplayName field of the RecipientRow structure ([MS-OXCDATA] section 2.8.3.2).