The genius tip for cleaning the washing machine drawer: it will be free of mold like new

Clean the detergent drawer

This cleaning is necessary at least once a week to remove any excess detergent that could later become smelly and musty. Beware of the self-cleaning function: many devices have this option to eliminate bacteria build-up and clean the drum at a temperature of 70°C. But, it does not always offer the expected result.
Leave the door open after the wash cycle

Golden rule: always remember to leave the washing machine door open after washing your clothes, to properly ventilate the drum. If you keep it closed, air won't get in and bacteria will grow from excess moisture inside.
Wipe the door seal after each wash

Speaking of humidity, also make sure to dry the rubber seal on the door. Use a clean cloth to do this after each wash. If you fail to do this, water in the joint can quickly cause bad odors.