Game developers get hundreds of game suggestions every day, whether they read them all or not is another matter.
I think you need to get into the industry and establish yourself within a developement company before they will take you seriously. You will probably need to do a university course in game design or whatever. Or apply for a job within their company that doesnt need a qualification such as that, like a basic admin role. Atleast then you'd be in the door and able to talk to the people who matter one on one.
But still, i don't think many games companys are looking for new ideas, because they always seem to have their own projects going on. Whilst completing one title, they'll no doubt have already started work on their next one.
If you've already gotten you suggestions written down, i can't see the harm in sending the document file to the companies e-mail address, but i doubt you'll get more than a acknowldgement e-mail back.