Apparently, Bruce Holland Rogers has been selling his flash fiction via e-mail for a few years.
I took a look at his website - http://www.shortshortshort.com/
Here's what he says about his flash fiction e-mail service:
Since January 2002, for just ten dollars U.S. a year (twelve Canadian, ten euro, or six pounds sterling) subscribers have been receiving short-short stories by Bruce Holland Rogers in their email boxes. Most of these readers must like what they're getting, since the majority renew. Stories go out three times a month, and they are an unpredictable mix of literary fiction, science fiction, fairy tales, mysteries, and work that is hard to classify.
Thirty-six stories for ten dollars. That's about twenty-eight cents a story.
Subscription stories are between 200 and 2,500 words long (with rare exceptions). Most of the stories distributed so far have been between 500 and 1500 words. Bruce's ideal is to send a story that readers can enjoy in a minute or two.
The stories arrive as unformatted e-mail text, which makes it easy to read them on a variety of devices. Paying subscribers are allowed to forward stories to other readers (although distribution by those recipients is prohibited...unless they subscribe).
There's also a 'Sample Stories' section, so that his clients can have an idea about what they'll be getting in their e-mail.
On that blog post I've mentioned earlier, Rogers claims his business is successful, and points out what he perceives as being other benefits to selling his flash fiction via e-mail - one of them is what he calls 'Double dipping':
After a story has been seen by my subscribers, it still can’t be found by any member of the public who wants to see it. There’s no publication of record. So has it been published? Most magazines and anthology editors have said no, my e-mailed stories are not yet published, and those editors are willing to consider the e-mailed stories for more traditional publication. I credit such publication as “first time in print.” So I’m paid twice.
Although it's obviously not possible to know how much of this is just marketing, one question seems unavoidable to me: