The ImportPerUserReadStateChange method toggles the read state of a list of messages.
HRESULT ImportPerUserReadStateChange(
ULONG cElements,
LPREADSTATE lpReadState
);
See Return Values.
In addition, ImportPerUserReadStateChange can return one of the following values:
The ImportPerUserReadStateChange method is called by the synchronizer for each message that is changed. This method should not be called from the agent.
IExchangeImportContentsChanges, PR_SOURCE_KEY, READSTATE