Topic Last Modified: 6/8/2004
Transport envelope properties for a MailMsg object are indexed using DWORD identifiers. Event sinks can allocate ranges of identifiers to store custom properties in the MailMsg object. The AllocPropIDRange is used to reserve a range of identifier values, and the EnumPropIDRange method is used to enumerate the values of a particular range. These ranges are uniquely identified (scoped) using a supplied globally unique identifier (GUID).
When implementing a transport event sink or sinks, use AllocPropIDRange to reserve a set of custom identifier values if your application needs to persist envelope properties for each MailMsg object handled. These properties are uniquely scoped using a GUID value, and remain with the object for the duration of its transit through the transport system. Use the EnumPropIDRange to identify the currently reserved property identifier ranges identified by various GUID namespaces.