PidLidValidFlagStringProof Canonical Property

Applies to: Outlook 2013 | Outlook 2016

Validates whether the dispidRequest (PidLidFlagRequest) property's value was set by an agent who knew the value of the PR_MESSAGE_DELIVERY_TIME (PidTagMessageDeliveryTime) property.

Associated properties:
Property set:
Long ID (LID):
Data type:


On non-sendable objects (received mail and non-mail objects), clients should set this value to the value of PR_MESSAGE_DELIVERY_TIME when modifying dispidRequest.

Since the value of PR_MESSAGE_DELIVERY_TIME cannot be predicted by the sender, if the value of this property is equal to the value of PR_MESSAGE_DELIVERY_TIME, it is reasonably certain that the value of dispidRequest did not originate from the sender of the message. A client can decide how to present the value of dispidRequest to the end user based on the result of this comparison in accordance with the specific security policy of the client. If the value of dispidRequest is ignored due to the presence of a value for dispidFlagStringEnum (PidLidFlagString), this property must be ignored.

Protocol specifications


Provides property set definitions and references to related Exchange Server protocol specifications.


Specifies the properties and operations related to flagging.

Header files


Provides data type definitions.

See also

PidTagMessageDeliveryTime Canonical Property

MAPI Properties

MAPI Canonical Properties

Mapping Canonical Property Names to MAPI Names

Mapping MAPI Names to Canonical Property Names