To "Todd" the Timid, Adam-Troy Castro's correspondent:
According to Adam, "Todd" wrote him expressing concern that, and I quote,
First of all, let me say that I don't think well enough of myself to be
paranoid (why bother being out to get me?) but something happened that
made me wonder. I submitted a story to (THE MAGAZINE) late one night
and had the rejection before dawn the next morning. I cannot imagine
(THE EDITOR) sitting up all night reading through his slush pile. The
only thing I can think is that he has a filter on the e-mail addresses
of people he has already rejected and kicks those over to the
auto-responder. Does this sound reasonable to you?
Adam was nice to Todd. He told him there was no blacklist and gave him four options that could have caused the rapid rejection response.
Todd, the truth is, you sent your work to somebody who was doing his or her job efficiently. The chances you've landed on any type of blacklist are slim and none. The real truth is that writers choose to not send their work to editors, not the other way around - any writers with any sense, that is. Now, this can be because they consider the editor to be beneath themselves due to the editor's poor behavior and poor quality of product (rare, but it does happen), it could be because the writer senses that the publication isn't the best fit with their work, or it could just be because they have found others with whom their work and taste is much more in accordance. The sooner writers wake up and smell the coffee, the sooner they can get down to their work, which is writing.
As to short fiction, Todd, that has been a hobby and pastime for many years. There is no such thing as anybody writing short fiction for a 'living' these days, not even in rich America, and most certainly not in other countries around the world.
Putting that truth aside, Todd, the last thing you should be worried about is why your story was rejected. You should also be grateful that the editor was so on-the-ball that your story was back to you to put to useful purpose the next morning after you sent it.
Todd, when you send your work to any editor, you are proposing a business transaction. Not a friendship, not a "hey, do ya like me?" offer, and not any type of commentary on your personal worth, or, this is the most important: on your abilities as a writer.
From all that I can determine, the great Robert A. Heinlein appeared only four times in The Saturday Evening Post. Three stories appeared in 1947 - "The Green Hills of Earth," "Space Jockey," and "It's Great to Be Back." "The Black Pits of Luna" appeared early the next year. I freely admit to have never read three of the stories, but "The Green Hills of Earth" was definitely written in a manner to reach a very broad audience. That was the audience for that magazine - a very different and less-specialized audience than the other magazines in which Heinlein's stories appeared frequently, which, prior to "The Green Hills of Earth" appearing in 1947, had been almost exclusively in Astounding - like from 1939 to 1947, so eight long years.
Short fiction is undergoing a bit of renaissance now, Todd. Some people's short fiction collections have been on bestseller lists this past year. Not SF/F stories, but other, "regular" stories. Everyone has had a lot of chitchat the last few years about what a bad state short science fiction and fantasy is in; it's hardly the "go-to" place these days. However, even the poor state of short science fiction and fantasy, the crappy pay, the low readership and the uncertain treatment shouldn't discourage you, if writing stories is your heart's desire.
All of this is by way of saying, be glad that editor got back to you so quickly, Todd. Get that story in circulation elsewhere, as fast as possible.
And that said, do these editors a favor, Todd. Read their publications. Look at the type of work that appears in them. This will give you an idea of the audience and the types of stories they enjoy. Picking work that makes their audience happy and satisfied is the editor's job, Todd. Writing things that the audience will enjoy - is yours.