Supporting Named Properties
Any object that implements the IMAPIProp : IUnknown interface can support named properties. Support for named properties is required for:
Address book providers that allow entries from other providers to be copied into their containers.
Message store providers that can be used to create arbitrary message types.
Named property support is optional for all other service providers. Service providers that do support named properties must implement name-to-identifier mapping in the IMAPIProp::GetNamesFromIDs and IMAPIProp::GetIDsFromNames methods. Clients call GetNamesFromIDs to retrieve the corresponding names for one or more property identifiers in the over 0x8000 range and GetIDsFromNames to either create or retrieve the identifiers for one or more names.
Service providers that do not support named properties must: