You can usually contact them them through twitter and such like but some do have emails which you can send stuff to.
Usually we don't provide emails on the wiki so that people can't spam them as those are usually reserved for more official stuff and buisness requests.
Hi! I'd just like to say that they do not restrict for their emails to be used just for business requests and official stuff, because I have written an email to Eve in English, and most of it consists of something a fan would say and he replied! You have to find them through NND, although some of their emails will not be displayed. Just so you know, Eve actually worked hard to reply to my english email and it took him 3 days to translate it. :~)