Thank you sir, may I have another!

I received a rejection from an agent this morning - one I'd queried only last Thursday. It was only a form letter rejection -- being rather pessimistic lately I just knew it was a rejection even before I opened it--but it's remarkable how grateful I was for the response. I even considered replying with a short, sweet "Thank you for your response," but I'm sure the last thing any agent needs is me clogging up their inbox and taking time away from their ability to peruse a query letter from some other poor slob waiting for their response.