親展しんてん書留かきとめ郵便ゆうびんでしょう
shintenkakitomeyūbindeshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of 親展書留郵便

1. Registered mail, likely.; Probably sent by registered mail.

Polite
Presumptive
Conjecture
Computing