Unsealed Letter
Open a letter that's been sealed already, it becomes an unsealed letter.
かいふう
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
開封前の商品であればいつでも返品可って書いてあるけど、開封後に中身が壊れてたり、その商品が好きじゃなかった場合はどうなんだろう。
It says I can return unopened products at any time, but what if I opened it and the stuff inside was broken or I didn’t like it?