Hi and thanks for answering this. My friend sent me a letter, and at the end he wrote "Qùo Zháng Láo" before he wrote his name to end the letter. I might have some of the accents a little off, but I was wondering what it meant. I can usually figure it out, but I am having a little bit of trouble with this one. Thank you so much.
Thanks for your question.
Unfortunately, there's no such phrase in Mandarin Chinese as you posted in your question. And "Qùo" is illegal syllable in Mandarin Chinese phonology system.(Consonants like "j", "q" and "x" cannot be combined with "u" or "ü" in Mandarin). So I suggest you checking your letter again and just seeing what it was presented.
Generally, the formats or phrases being used at the end of letters/e-mails are kinda flexible, but Chinese native speakers often use nouns which reflect the relationship with the addressee. For example, if I was your friend, and I wrote a letter to you, I might write "友/Colin" ("友" means "friend") and date as the last words of this letter. Of course, you can use some polite and conventional remarks such as "盼望早日回信"（Hope hearing from you as soon as possible）, "万望示复" (literally speaking, esp. in letters which subordinate writes to his superior, means "Please reply my letter with many expectations") etc.
In addition, if your Chinese friend wrote you with Chinese characters, you can paste the characters of "Qùo Zháng Láo" and send to me, perhaps in that way, I can offer you more practical information for you.
It's my first answer in AE, and I hope it can do you a favor. Thank you.