定形 ていけい がい郵便 ゆうびん ものでしょう
teikeiga i yūbimmonodeshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of 定形外郵便物

1. Probably non-standard mail.; Probably surface mail.

Polite
Presumptive
Conjecture