彼は書信を通じて遠方の友人と連絡を取り合っている。
He keeps in touch with his distant friends by letter.
留学中の娘から久しぶりに書信が届いた。
A letter finally arrived from my daughter, who is studying abroad.
二人の作家が交わした書信が一冊の本にまとめられた。
The letters exchanged by the two writers were collected into a single book.