Any object that implements the IMAPIProp interface can support named properties. Support for named properties is required for:
Named property support is optional for all other service providers. Service providers that do support named properties implement name-to-identifier mapping in two IMAPIProp methods, GetNamesFromIDs and GetIDsFromNames. 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: