Very polite! Some quick corrections: I checked our last email in which you attached the letters and said the original ones had been sent. This was more than two weeks ago so I'm a little worried it might've gotten lost. If you could you please check the mail whenever it's convenient, I'd really appreciate it!

@Brian, Thank you so much for point out this mistake, very useful!

不好意思，稍微提醒一下：英文有時候加個冠詞，意思會完全改變："To ask a help" 的意思是「請傭人幫忙」(a help = a domestic help = 傭人). It is safer to write "Is it correct and polite to ask for help?"