Not many large publishing houses accept queries directly from writers. Most big houses won't read a manuscript unless it comes through an agent, but there are times that it seems easier to get a rocket to the moon than to get a manuscript to an agent.
Not a problem with Kensington Books. If you check out their submission guidelines, you'll discover that they accept queries for fiction and non-fiction, but they no not publish science fiction, fantasy, or poetry.
If you want to send them a query for fiction, they ask for the first three chapters and a synopsis no longer than five pages.
For non-fiction, they require a cover letter, query, and summary -- along with the writer's qualifications and connections as they pertain to the book's content.
You may query only by e-mail -- no attachments, and if an editor is interested, he or she will respond based on the material you sent in your query.
They state to allow at least three months for a response. If you wait a long time without hearing from them, it generally means they are not interested.
If you're interested in finding out more about Kensington Books, here is the link for their submission guidelines. http://www.kensingtonbooks.com/finditem.cfm?itemid=14298