Well, I was not between her and the mailman, but I will remember that in the future. I'm not sure if she thinks it is her job to "protect" us. Remember, Dallas is afraid of everything/everyone.
Unfortunately no, he does not come at the same time every day, which is annoying.
We could crate her if we knew when he'd be coming each day, but then she wouldn't learn not to go bonkers when he/she comes. On the other hand if we did crate her, my house wouldnt' get destroyed