Yes. Being homozygous black, she will NEVER be able to produce a red based foal. Chestnut/Sorrel, Palomino, Red Dun, Cremello etc. Anything that is e/e. Your mare will only be able to produce E/e foals (or E/E depending on what she's bred to) So her resulting foal will always be black based like black, bay, grulla, perlino, buckskin, etc.
"The greatest pleasure of a dog is that you may make a fool of yourself with
him and not only will he not scold you, but he will make a fool of himself too."