I agree with Rachel and Sue...I've never even thought about including a Boxer in the group with some of the more "protective" dogs. In fact, I wouldn't even include Bulldogs, having grown up with one.
You just need to broadcast the word..."My Boxer is not mean" and encourage and correct people when they say something different. I have two Golden Retrievers and one happens to be very unpredicatable...I'd never let her near strangers or encourage people to come close to her, so you just never know. She barks and growls at strangers and who would ever think of that from a Golden Retreiver?
Keep your chin up and give your baby a big hug from Helen and me!
Logan