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2.2.1.11 PidLidValidFlagStringProof Property

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Type: PtypTime ([MS-OXCDATA] section 2.11.1)

The PidLidValidFlagStringProof property ([MS-OXPROPS] section 2.348) MUST NOT exist on meeting-related objects. On objects that are not sendable (received mail and objects that are not mail), this property is optional. If present, this property is set equal to the PidTagMessageDeliveryTime property ([MS-OXOMSG] section 2.2.3.9) when modifying the PidLidFlagRequest property (section 2.2.1.9). Setting this property is optional for the client. The server does not read or set this property.

This property can be used to validate whether the PidLidFlagRequest property was set by an agent with knowledge of the value of the PidTagMessageDeliveryTime property. Since the value of the PidTagMessageDeliveryTime property cannot be predicted by the sender, if the value of the PidLidValidFlagStringProof property is equal to the value of the PidTagMessageDeliveryTime property, it is reasonably certain that the value of the PidLidFlagRequest property did not originate from the sender of the message. A client can decide how to present the value of the PidLidFlagRequest property to the end user based on the result of this comparison in accordance with the specific security policy of the client.

If the client ignores the PidLidFlagRequest property due to the value of the PidLidFlagString property (section 2.2.1.10), the client also ignores the PidLidValidFlagStringProof property.