Thanks for not liking my work. No, sincerely, thanks.
The first time I received a rejection letter, I was elated. It meant that I had tried. It meant that I had actually completed a project, reworked it to the point that I thought it was ready to share with the world, and sent it out to a major publication. And somebody at that publication read it. They didn't like it, but they read it.
I counted that as a win. I had (possibly) overreached, but that rejection validated me: I was officially a "struggling writer!"
That first rejection was swift and impersonal. An email, it said my piece "wasn't a good fit" for their publication. Fair enough. Since I was now a writer, and this sort of thing comes with it (I'd read), I shook it off, and created an email folder (and later a spreadsheet) called "Submissions." I sent out a few more attempts: some articles, some short stories. Within months, I had a few more rejections; not many, but exactly equal to the number of pieces I had sent out.
It didn't bother me, well not much. While each "no" was proof that I had tried, it was also proof that I had only tried a few times. Shouldn't I be trying more? If I really wanted to be a real-live published writer, shouldn't I be trying harder, getting more rejections?
Of course I should. But, my (very slowly) mounting pile of rejections has taught me a lot. Some of them were generic rejections. Others were personalized, that is, form letters with a personal note at the bottom that encouraged me to keep going. Some said I was this close. Some gave a tip to improve, or a short reason why they didn't accept my work. Wrong publication, some said. Too much exposition, one said. "The story really starts on page 4." (The story in question was 6 pages long, so...). But all of them, even the impersonal, automatic replies, got a thank you back from me.
And here are four reasons why you should thank your rejectors too:
1. Don't burn bridges. If, no, when I finally wrote something that was the right fit, the right length, I didn't want the editor to remember the stinker I'd sent last year; anything except for my sincere thanks that they actually took the time to read my work the time that it wasn't either of those things.
2. Someone actually took the time to read it. They didn't like it, but they read my work. That's amazing.
3. Someone gave you feedback. A real, live, professional in the publishing industry gave me useful feedback for free. Those ones got an extra-nice thank you.
4. They might have sent the wrong email. True story: the first time I was paid (very well) for a piece, the editor rejected it, flat-out. I sent him a thank-you-anyway, and within an hour, I got a "Oh my gosh, we meant to accept that one" response, and an offer of remuneration that paid for a Le Creuset pot, which will last forever as a memento of the first time I made serious money from writing.
So, enjoy those rejections, every single one! They are your evidence that you're trying. And don't forget to be polite.