From his pocket Bland takes an unmarked envelope that is not sealed.

The chief handed him the unmarked envelope containing his personal effects.

On a monthly basis, he would send them several thousand dollars in an unmarked envelope as appreciation for their attempt at raising him.

Others came in an unmarked brown envelope.

Five hundred dollars a month, in an unmarked envelope.

A project in first grade required each student to bring one white, unmarked envelope to school.

Unfortunately, he left the unmarked envelope containing the money in the seat of the taxi he took to the bank.

He stared at the photo for a long time, placed it in an unmarked envelope, set that in a lower drawer of his desk.

Khromchenkov handed a large unmarked envelope to his fellow minister and left the room.

It arrived by mail in an unmarked envelope, and I'm sure the same thing happened with Bowman.