書留

1. Origins, structure, and basic meaning

• Structure: 書留 is a noun read かきとめ for registered mail, whose handling and delivery are recorded.
• Basic usage: 書留で marks the mailing method, while 書留 can also denote an item sent by that method.
  • In 大切な書類を書留で送った。, it is the means of sending; in 書留を受け取るために印鑑を用意した。, it is the registered item being received.

2. Common pitfalls and similar expressions

• Difference between で and を
  • で in 書留で送る marks the mailing method, while を in 書留を受け取る marks the registered letter or document received.
• Service and mail item
  • Depending on context, 書留 can mean the registered-mail service or the letter or documents sent through it.
• 書留 and 書き留める
  • 書留 is a postal noun. 書き留める(かきとめる), “write down and keep a note of,” is related in sound but has a different grammatical role and meaning.