
Here are my FIVE all-time favorite epistolary novels:

These is My Words: The Diary of Sarah Agnes Prine 1881-1901, Arizona Territories by Nancy Turner
In the first entry, Sarah is seventeen with poor grammar and a penchant for telling larger-than-life stories about her trip to the heathen land of the Arizona Territories. Her family carries along its future in the form of pecan saplings. Her voice matures over the years as she writes about settling into such a wild land--the good and the bad that shape her. What I loved about the story was the author's ability to grow her character over time. (monologic)

Alice Bullock is a newlywed when her husband up and joins the Union army and leaves his bride with her formidable mother-in-law on an Iowa farm. Alice tells all to her sister in lively letters that reveal a changing relationship with her mother-in-law, accounts of local quilting bees/gossip, and the rigors of rural life. (monologic)

The Screwtape Letters by C.S. Lewis
Mr. Lewis wrote the original Letters as a serial for an Anglican magazine. He didn't enjoy the experience and promised never to use the epistolary form again. I'm so glad he completed his commitment. Screwtape, a senior demon, mentors Wormwood who has just been assigned a "patient." The power of the letters is their up-side-down look at the spiritual realm. Lewis manages to mentor his readers in the subtlety of evil with his satire. A classic. (monologic)
The Guernsey Literary and Potato Peel Pie Society by Mary Ann Shaffer and Annie Barrows
My first impediment to reading this novel was its title. I still can't say it without reading the title off the cover. Once I forgot the title--easy for me--I fell in love with the story. The co-authors manage to write an engaging story set just after WWII with multiple voices--letters flinging hither and yon. The main character is writer Juliet Ashton, looking for her next writing project. Along comes a letter from a man she doesn't know because he discovers her address on the leaf jacket of a beloved book. He hopes she can help him find more of his beloved author. A friendship ensues, around books, and Juliet's life is changed forever. The satisfaction in reading this novel came from the voyeur (of the nicest sort) experience this story provides.

The Diary of Mattie Spenser by Sandra Dallas
Yep, two by the same author. In this novel, Mattie is surprised to be the choice of her Iowa town's most desirable bachelor. She marries him within a week and heads for the Colorado Territories in the 1800s. What she experiences is a distant husband and the hardship of carving life out of the prairies. I may love this story because it's about Colorado, my home state. Although never convinced of my ability to settle anything, least of all a prairie with "too much sky," this book convinced me I am a 21-Century woman who better not complain about traffic in Denver. Some of Dallas' motivations are weak, but this is a powerful look into the isolation of prairie life for women. (monologic)
So those are my favorites, but if the list had been longer, I would have not had trouble filling it with more titles. Do you enjoy the epistolary novel? Why so? Which epistolary novels make it to your list of favorites? I need to add more to my list, so please be generous with your titles.