CanonicalName:	PidTagImportance
PropertyID:	$0017
DataType:	PT_LONG
MAPINames:	PR_IMPORTANCE
Area:	General messaging
Description:	Contains a value that indicates the message sender's opinion of the importance of a message.
Remarks:	This property and the PR_PRIORITY (PidTagPriority) property should not be confused. Importance indicates a value to users, while priority indicates the order or speed at which the message should be sent by the messaging system software. Higher priority usually indicates a higher cost. Higher importance usually is associated with a different display by the user interface. This property can have exactly one of the following values: IMPORTANCE_LOW - The message has low importance. IMPORTANCE_HIGH - The message has high importance. IMPORTANCE_NORMAL - The message has normal importance.