Steve: I've been corrected since I posted Rands. Epistolary poetry, so I'm told:

“The epistolary form can add greater realism to a story, because it mimics the workings of real life. It is thus able to demonstrate differing points of view without recourse to the device of an omniscient narrator. An important strategic device in the epistolary novel for creating the impression of authenticity of the letters is the fictional editor.” [Epistolary novel]