As is true of New Testament epistles generally, the address of Revelation contains three elements: the writer, the addressees, and the greeting. [source][source][source]
Thomas argued that the genre of Revelation is prophecy written in epistolary style. [1] Swete saw it as a prophetic vision and a letter (from Revelation 1:4 on). [2] Beale viewed it as an epistle that contains apocalyptic and prophetic material. [3] Beasley-Murray, and Carson and Moo, also advocated a combination of apocalyptic, prophecy, and epistle. [4] Most scholars have classed it as apocalyptic. [5] I prefer to think of it as an epistle containing prophecy, much of which is apocalyptic. [source][source][source]