Bring a large pot of lightly salted water to a boil and cook your macaroni according to the directions on the package. When ready, drain and rinse the pasta under cool water.
While the pasta boils, prepare the dressing. Place the mayo into a small mixing bowl and add the chopped pickles and celery, pickle brine, lemon juice, fresh dill, salt, and cracked black pepper, then mix it until it's well blended.
Transfer the cooled macaroni to a large serving bowl. Add the creamy dressing, the mackerel, and the sliced scallions to the bowl, then using two large serving spoons, toss to coat the noodles.
Garnish the salad with some extra fresh dill. Refrigerate for a few hours so the flavors can mingle. Serve as a summer side or enjoy it as lunch!