Will "Store Driver Delivery Agent" be available for customization in feature Exchange Version

[kenizhou]

I noticed that there are more Agents interfaces (e.g. Store Driver Delivery Agent )are exposed to public in "Microsoft.Exchange.Data.Transport.dll".  does it mean these agents will be available for third party customization?

Thanks in advance. 

[#2]

As of now, Exchange only supports Receive, Routing and delivery  3 types transport agents. Will "Store Driver Delivery Agent" be supported in future? anybody knows.