Goodgulf:
I've written (or mostly written - still revising parts of it) a new story as an experiment. I'm trying my hand at a new to me story form; I'm trying to write an epistolary story, which is either a series of letters or an exchange of letters.
When dealing with the first bit of it, the basic setting, has to explain why letters are being written. I felt I had to:
a) set it in 1995 (before most of the world had email),
Well, because I'm both lazy and relatively 'low-tech,' this is how I'd handle it--in fact did handle it exactly (using the 1995 date) in my "Letter Challenge" story.
Handwritten letters generally include the date they were written, so the whole explanation for the use of 'snail mail' would be contained right there.
Of course, if the story requires some reference to 21st-century technology, then the earlier setting obviously wouldn't work effectively.
To me, the mid-'90s time period would be the 'Occam's Razor' reasoning for the use of 'snail mail' by the letter-writers in an epistolary account...

--C.K.