Once upon a time, rejection letters from literary magazines came on slips of paper of different sizes and colors. I have a sheaf of the 'best' ones--where the editor scrawled either his initials, or something like sorry on the standard 'thanks but no thanks' slip--which I took to mean that someone thought enough of my work to encourage me.
I mean, they see a lot of crap, right? I've read for magazines. It's enough to turn you into Simon Cowell.
My best rejection letter is on pretty, parchment-goldy paper. This was for a set of poems, back when I was writing poetry regularly. I won't name the magazine. The editor hand-wrote me a letter for each set of rejected poems, the fourth one saying, "these came pretty close." Be still my heart! The fifth one, I decided, would be it. If I didn't get in, it wasn't meant to be.
Helen W. Mallon (he wrote),
The problem here lies not in the technique but in the tenor...As an editor I have made it my position to publish only work that indicates...the life is worth living, that existence is a positive process. Those writings of yours I that I have seen do not fulfill--to my sensibilities--those requirements. Thank you for your continued interest.
I've been called a lot of things, but depressing isn't one of them. Well, that was the first time. This made me laugh so much it's probably the one rejection I least minded getting.