In researching how to use Exchange Web Services, I see examples like this
Dim PR_DELETED_ON As New ExtendedPropertyDefinition(26255, MapiPropertyType.SystemTime)
Dim PR_SEARCH_KEY As New ExtendedPropertyDefinition(12299, MapiPropertyType.Binary)
That first parameter is an int that represents the property ID. Can anyone give me a pointer to where those ID numbers are defined?