I'm getting some nice rejections while I'm querying to find an agent for my Victorian ghost novel. I wrote a thank you notes to the last two agents who said No and then wondered if I was just wasting my time, and theirs. How do you feel about getting a thank you if you've sent an author a quick or thoughtful rejection?
It's never wrong to say thank you according to the Deportment Enforcer at Miss Blanche's School for Sharks.
I think the reason you hear "don't respond to rejections" is two-fold. Some people's idea of "thank you" involves "I'll show you, SharkForBrains, and boy you'll be sorry you passed on the next JeffSomers/LairdBarron/Patrick Lee."
That's not a thank you so much as it is a Bronx cheer, and frankly I can do without that at 3 in the morning which is when they tend to roll in.
The other reason is that it's one more email when my fiercest goal (today and every day for the last two months) is to get my inbox under 300.
I will say that responding to a form letter is not required even by such etiquette stalwarts as the always-correct, always-gracious Miss Blanche. A polite, short thank you to a personal reply is never a waste of time. If anything it's a reminder that most people who get in touch with me are thoughtful, eager writers who just want me to read their work carefully.