come in over the transom

Arrive as an unsolicited communication, most often a manuscript submitted to a publisher. The transom referred to is a small window above a door and was found in many offices before the advent of central air conditioning. Although the literal meaning has vanished with the existence of transoms, it continues to be used for manuscripts not submitted through an agent or requested by an editor. With the increasing development of self-publishing, the cliché may be heading toward obsolescence. However, it is still used sometimes for other matters, such as “We’ve had nearly one hundred job applications come in over the transom.”