We are working on the slush pile for the issue. Surprisingly, I've read more than one epistolary story this year. An epistolary story is a narrative told via a series of documents. In the old days, these would be letters. Later, newspaper or magazine clippings, book excerpts and/or some combination of all of these, became popular.
Horror has a lovely epistolary tradition including Carrie by Stephen King and Dracula by Bram Stoker.
Nowadays, anything goes. The story could be told via blog posts, texts, tweets, (descriptions of) streaming videos, or whatever else you can imagine. I love the creativity behind these ideas. And many of the high-tech versions lend themselves well to science fiction.
However, I do think it's difficult to evoke an emotional response in a reader via documents. It's particularly difficult with experienced speculative fiction readers (like editors!). Furthermore, many of these epistolary stories utilize surprise endings. Sadly, it's difficult to surprise editors.
So, bottom line: please do send us your epistolary stories.
But make sure they're excellent!