Pat the salmon filet with a paper towel to remove any excess moisture from the salmon. Set aside.
Add the maple syrup, mustard, garlic powder, and coarse sea salt to a bowl and whisk the ingredients together.
Place the salmon in a gallon bag or a deep dish and pour the marinade over the salmon. If you are placing the salmon in a deep dish, be sure the salmon is skin side up so the meat is sitting in the marinade.
Place the salmon in the refrigerator to marinate for at least 1 hour and up to overnight.
Preheat the smoker to 225ºF and remove the salmon from the refrigerator. Let the salmon sit at room temperature for 10 minutes.
When the smoker is ready, remove the salmon from the marinade, allowing excess marinade to drop off the salmon. Set marinade aside for later.
Place the salmon filet skin side down to the smoker and smoke the salmon for 1 hour at 225ºF.
While the salmon is smoking, prepare the cream cheese spread. Add the softened cream cheese, dijon mustard, and maple syrup to a bowl and mix until smooth. Set aside.
After 1 hour of smoking, brush the salmon filet with the remaining marinade and increase the smoker temperature to 375ºF and smoke the salmon filet for an additional 10 minutes.
Remove the salmon from the smoker when the internal temperature reaches 145-150ºF.
Let the salmon rest for 15 minutes.
Serve immediately with the cream cheese spread Eat or place the salmon in the refrigerator to cool and serve cold.