親しん展てん書かき留とめ郵ゆう便びん

• 書かき留とめ

  書留 is general registered mail, while 親展書留郵便 specifically requires delivery to the addressee in person with proof of receipt.

• 親しん展てん

  親展 means 'confidential' or 'to be opened by addressee only', often used on envelopes; 親展書留郵便 is the full postal service term.

Compound of 親展 (confidential, to be opened by addressee only) + 書留 (registered mail) + 郵便 (postal service).