Meanings
A transom is a lintel or crosspiece over a door; likely an alteration of Latin trānstrum (“crossbeam”). Refers to the idea of a writer tossing a manuscript through the open window over the door of the publisher's office. Alternatively, a "transom" is the nautical term for the back of a small boat. Something which "came in over the transom" would have suddenly (and presumably, surprisingly) entered through the "back door" of the craft, metaphorically.
Unsolicited.
Meeting a deadline by delivery after the day of the deadline but before opening of business the following business day.
Example Sentences
1
The author received several manuscripts over the transom.
2
I wasn't expecting any job offers, but one came in over the transom.
3
The lawyer received an anonymous tip over the transom.
4
The company decided to hire a candidate who applied over the transom.
5
The editor discovered a talented writer among the manuscripts sent in over the transom.