Rude, Thoughtless and Annoying (Almost as bad as ELP)

Over the past seventeen years I have been sent a lot (technically more than two, but a lot more than two... and so on) of fiction submissions for Albedo One magazine. From early on we accepted email submissions because we are out on the borders of civilization (Ireland) and contacting us by post is very expensive. To illustrate the postage problem it costs about five times more postage for us to send out a subscriber's copy of the magazine than it does for Galaxies in France, more than twice the cost of printing an issue, even with all the ancillary costs added on. The postage costs also meant that we were getting a small number of submissions per month (less than a hundred) and we felt more submissions would help to raise the quality of fiction in the magazine. Accepting emails immediately increased the number of submissions and has genuinely contributed to an increase in the quality of stories we have to choose from.
However, I have a couple of observations about email submissions. And both of them, in my mind, relate to care and attention.
The first point is that there is a significantly higher acceptance rate of stories submitted by snail mail. What this suggests to me is that some writers, a lot in fact, take less care with their stories if they are submitting by email. Or maybe they will only send stories they are more confident about by snail mail. Or perhaps the ease of submission means writers are not truly polishing their stories before sending them out. I don't know. It's just a thought backed up by little in the way of evidence. However, I'd be interested in hearing from other editors who accept both snail- and e-mail submissions. Is there a similar correlation of quality in your submitted stories?
My second observation refers directly to the title of this piece (though not Emerson, Lake and Palmer who were merely due a dig) and is aimed directly at writers.
Of late I have been getting a lot (not as much as the previous lots but a significant number all the same) of stories sent by email without even a Dear Sir or Hi at the front, never mind anything resembling a cover letter or even a request that we might read the enclosed story. I have even been sent blank emails with an attachment. These I delete instantly as we state in our guidelines that we do not currently accept attachments. But I'm thinking that in future if writers aren't even bothered to say Hi, or introduce themselves, or show even the slightest sign of investing in the social contract that for centuries has ruled communication, I think I'm going to dispose of these emails also. There is a statistic which suggests we won't be missing any great works of genius as to date none of these unlovely submissions has made it through the process.
So maybe rude equals untalented or maybe the writers who have time to observe the niceties of correspondence are also the ones who take care over their stories. I would be interested in comments from writers and editors alike because, really, I'm just thinking out loud here.
But I am reminded of a writer (in a film) who couldn't understand why his repeatedly frantic letters regarding publication of his book were being ignored. In the end he decided to write a letter which could not be ignored. It began: Dear Bastard...
I sometimes think that no greeting at all is simply shorthand for this.