2.2.1.29 PidTagNonReceiptNotificationRequested Property
Type: PtypBoolean ([MS-OXCDATA] section 2.11.1)
The PidTagNonReceiptNotificationRequested property ([MS-OXPROPS] section 2.880) specifies whether the e-mail sender requests a non-read receipt from all recipients (1) if this message is deleted without being read.