I'm not so sure they have a contact email address available to the public.(*) Given that Microsoft is well known around the world, it'd most likely be inundated with thousands of messages daily, making it unfeasible for them to mange. However, if you go to
their support page and click "ask the community," you can get advice there. Also, their phone number is on the site.
(*) If I'm incorrect about that, please override my statement if someone reading knows something I don't.
Edit - Silly me, I posted the link to the Store page. Fixed now.