Post
noun
Mail (or post) has convenience because it is sent for you in the mail (or the post!).
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. The reading of 便 (びん) in this vocabulary is an exceptional reading, so here's a mnemonic to help you out. You get a lot of junk mail so you throw it in the waste bin (びん). The waste bin is where junk mail goes.
おくさーん、郵便ですよー！
Madam, we have mail for you!
そこには明るい赤色の郵便ポストがありました。
There was a bright red mailbox there.
郵便番号は何番ですか？
What is the postal code?
郵便業においては、効率とスピードが全てだ。
Efficiency and speed are everything in mail service.