Users of Internet services need a better understanding of the mechanism of networking, especially communication protocols; however, many protocols are complicated and often oriented toward technical staff and those already familiar with network protocols. Accordingly, there is a need to facilitate understanding of protocols for learning and communication purposes. This paper introduces a schematic description of protocols in general, exemplified through the Simple Mail Transfer Protocol (SMTP). It produces a conceptual schematic depiction of SMTP based on the notion of flow of messages and signals in a system with six generic stages: creation, release, transfer, arrival, acceptance, and processing. The resultant conceptual picture is a systematic specification that assists in illustrating functionality and support comprehension.

network protocols, simple mail transfer protocol (SMTP), communication.