Cut one lemon into 6 thin rounds, and cut the rounds into half moon shapes. Juice the remaining lemons. Mix the lemon juice with the mayo, dill, garlic, and salt and pepper in a bowl.
Brush the mayo mixture over all the salmon filets. Cut squares of foil and put each salmon onto a foil square. Place 3 half moons of lemon over each salmon filet.
Wrap the foil around the salmon and place the packets onto a baking sheet. Bake for 10-12 minutes until the fish is just cooked and able to flake easily.