Recs if you like Kate & Frida...

"a novel written as a series of letters between the fictional characters of a narrative. The term is often extended to cover novels that intersperse other kinds of fictional document with the letters, most commonly diary entries and newspaper clippings, and sometimes considered to include novels composed of documents even if they do not include letters at all. More recently, epistolaries may include electronic documents such as recordings and radio, blog posts, and emails."

100 short books for when you need to break a reading slump or reach a reading goal.