epistolary

Adjective

  1. written in the form of or carried on by letters or correspondence; “an endless sequence of epistolary love affairs”; “the epistolatory novel”

Adjective

  1. Literature (of a literary work) in the form of letters an epistolary novel

Literary relating to the writing of letters.

Origin

mid 17th century: from French épistolaire or Latin epistolaris, from epistola (see epistle)