親展 しんてん書留 かきとめ郵便 ゆうびんだったら
shintenkakitomeyūbindattara

Noun
Da Copula

The "-tara" conditional form ("if/when…") of 親展書留郵便

1. If it were registered mail (delivered by hand); If it had been registered mail (delivered by hand)

Tara Conditional
Computing