Slush pile

In publishing, the slush pile is the set of unsolicited query letters or manuscripts sent either directly to the publisher or literary agent by authors, or to the publisher by an agent not known to the publisher.

Sifting through the slush pile is a job given to assistants-to-the-editors, or to outside contractors (called "publisher's readers" or "first readers"). If assistants find something interesting there and can persuade a more senior editor to consider it, they may get some credit for themselves, especially if the piece is subsequently published and sells respectably.