料金 りょうきん後納 こうのう郵便 ゆうびんでしょう
ryōkinkōnōyūbindeshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of 料金後納郵便

1. Probably post-paid postage.

Polite
Presumptive
Conjecture