February 14th to February 17th were not such good days. I got four rejections in those four days. 

I also discovered what the "form" letter is. And I am by now becoming quite familiar with it.

They all start and end a little differently, but somewhere in the middle of one or two or three short paragraphs, you inevitably see the words "not suitable for our list". They usually thank you for submitting your work and sometimes even use the word "decline", as if they somewhat sheepishly have turned down your very kind offer. I can't be sure, but I think there is a chance these form letters may be euphemisms for "your book sucks".

At the other end of the diplomacy spectrum are the blunter one liners, which have no place for euphemism, and which simply say "we will not be considering your book". 

And somewhere in the middle, you get the euphemism that delivers a body blow gently, one that sort of creeps up on you from behind, like this one: "the market is extremely competitive and we are only taking on books we can be 100% enthusiastic about". Again, I can't be sure, but I think there is a fair chance that what this really means is "your book sucks, a lot."

You put yourself on the line, putting your work out there. Apparently JK Rowling got 19 rejections before she found a publisher. I imagine even she must have had a moment or two of doubt.