“convenient / mail” in Japanese is 便, read ben, bin, tayo (べん, びん, たよ). It is a Grade 4 Kyōiku kanji, taught in year 4 of Japanese elementary school, and appears in words such as 便利 (convenient).
What does 便 mean?
この店は便利だ。
Same sound, different character — the classic trap. Compare them side by side: