Cook a large pot of salted water until boiling, add macaroni, and cook for 8-10 minutes until al dente. Drain and cool under cold water.

In a mixing bowl, whisk together mayonnaise, Dijon mustard, salt, and pepper until smooth.

Fold the cooled macaroni into the dressing and add bell pepper, celery, cherry tomatoes, red onion, and pickle relish.

Cover and refrigerate the salad for at least 1 hour before serving.