If the mold or mildew has already taken place, the best thing is to run a few cycles of bleach with no clothes in it. I would then run Affresh tablets at least twice a month. The door gasket needs a thorough cleansing front and black with some Clorox wipes. Regular maintenance is to clean the gasket once a week and run cleansing tablets regularly The issue is if the mold has taken place, it is hard to get rid of and will take some time.