Bring a pot of lightly salted water to a boil. Add macaroni, and cook for 8 to 10 minutes, until tender.
Drain, and set aside to cool.
Meanwhile i,n a small bowl, whisk together the Miracle Whip, Dijon mustard, salt, pepper, and celery salt.
Add the cooked pasta, diced red pepper, onion, and celery to large bowl. Toss together. Stir in the dressing and mix well.
Cover and refrigerate at least 4 hours or overnight.