Do you use liquids or gels at lower temperatures? This is why there are lots of complaints about washing machine odours.
It can be prevented by doing the occasional hot wash using powder. (Powders contain bleaching agents that prevent bacteria and moulds growing - liquids do not).
And -yes - leave the door and powder dispenser drawer open to allow air to circulate.
What I do is put a cloth in between thr drum and the seal when the wash is fi is finished. Water collects there and it can smell if not removed. I always put a scoop full of washing crystals in the wash it helps keep limes ale and germs at bay.
Carollinda