220.127.116.11 Post-Transmit Processing of a Flagged Message
If the value of the PidTagSwappedToDoStore property matches the value of the PidTagStoreEntryId property ([MS-OXCMSG] section 18.104.22.168) of the Message object, the client swaps the contents of the PidTagSwappedToDoData property (section 22.214.171.124) and the primary flag storage location, with the exception that if the PidTagToDoItemFlags property (section 126.96.36.199) is set to todoRecipientFlagged, then the dwToDoItem field of the PidTagSwappedToDoData property is set to todoTimeFlagged. After the operation, the previous contents of the primary flag storage location are now in the secondary flag storage location and vice versa. In addition, the PidLidValidFlagStringProof property (section 188.8.131.52) is set equal to the PidTagMessageDeliveryTime property ([MS-OXOMSG] section 184.108.40.206).
If the value of the PidTagSwappedToDoStore property does not match the value of the PidTagStoreEntryId property, the client clears the PidTagSwappedToDoData property.
In both cases, the PidTagSwappedToDoStore property is deleted.