1.
registered mail
A postal service that provides tracking and proof of delivery for important items.
書留 is registered mail that provides tracking and requires signature upon delivery.
Types of registered mail in Japan:
- 一般書留 (regular registered mail)
- 簡易書留 (simplified registered mail)
- 現金書留 (cash registered mail - for sending money)
Common expressions:
- 書留で送る (to send by registered mail)
- 書留料金 (registered mail fee)
The name comes from the fact that the mail is 'recorded' (書き留める = to write down/record).