I've been dealing with submission requirements a lot lately, and have noticed a three-tier hierarchy. First, there are the breezy dismissals of the Penguins and the Harper Collinses, who are always confident that they will get their hands one the next Literary Sensation and don't need to worry about the slush-piles of the developing world:
Hello! Our publication house accepts submissions through registered literary agents only. If you would like to read a book about how to get one of those, we'd be happy to sell you one. All the best in your endeavours! Cheerio!
The second tier is populated by the bluff cream-scoopers of the larger publishing houses, the ones who can afford unpaid interns:
We accept unsolicited manuscript submission on Fridays between noon and tea-time. All genres will be considered except the ones that don't sell. Please use standard manuscript format of some sort, and include a brief cover letter describing the book and so on. We might get back to you in six to eight weeks, but it's far more likely that you'll never hear from us again.
Then, last of all, is the vituperative list of all the things that the smaller publisher hates. Underlined words and threats abound. It's likely that this is the sort of publisher we would be, if we set up a small press:
Your submission MUST be in TNR 12 point double-spaced and use hanging first lines to indicate a new paragraph! If it isn't it will be PERMANENTLY DELETED! Do NOT send physical copies of your work to our address. We will NOT return them. We do NOT have time to comment on every single submission we receive so if your submission is unsuccessful you will NOT hear from us ever again! WHY DO I HAVE TO KEEP EXPLAINING THIS!!!!???? AAARRRRGGGGHHHH!!!!!!!
Dalek slush-pile interns are only a matter of time, my friends.