I'm currently reading this 1740 epistolary novel,
Pamela, by Samuel Richardson. Richardson (1689--1761) was a printer in London, and also wrote letter writing manuals instructing readers on how to write and behave properly. One of the letters in the manual sparked the plot of
Pamela, the first classic English romantic novel.
Pamela is told through a series of letters from Pamela, a beautiful and godly servant girl, to her parents, beginning with her master's attempts to seduce her. According to
this documentary by the fabulous historian Lucy Worsley, which goes into more detail about the success of the novel, Richardson was one of Jane Austen's favourite authors, and Pamela inspired her writing as well as the writing of other love novels.