SMTP Service Extension for Message Tracking
The Message Tracking Models and Requirements document [RFC-TRACK- MODEL] discusses the models that message tracking solutions could fol- low, along with requirements for a message tracking solution that can be used with the Internet-wide message infrastructure. This memo defines an extension to the SMTP service that provides a message tracking solu- tion that satisfies those requirements. Using the model document's ter- minology, it uses active enabling and active requests with request referrals.