That's just a rule.
Not even if you think they are "glowing."
Not even if the rejecter suggests you try another market.
It's bad salesmanship for starters, and it makes me realize before I've ever read your stuff that it isn't something everyone is dying to get their mitts on.
Most of the projects I'm offering on these days have three or more agents in the mix, offering representation.
I'm not looking for a diamond in the rough.
Don't quote your rejection letters.