When we got home at the end of May after being gone for 5 weeks I discovered when I opened my washer that it stunk... (big time!) If I leave the door to my washer ajar it swings wide open ... So my high tech solution is two rare earth magnets and a good elastic band. The smell is now gone... and by accident I'm actually using a liquid HE detergent!
If you want more info here's a good article on 'problems' with front load washers!