Dear my friend,
I see that you are searching for users with an active GSM/data connection on their smartphone, and Vietnam is one of the countries whose users you need.
I am a native Vietnamese speaker, and I am also fluent at English speaking and writing. I am almost always active, and I am capable of maintaining connection with people all day. For the reasons mentioned, I believe that I am a good fit for the job. I assure you that I could help you handle the job excellently under high pressure.
In case you need me to do the job, please kindly inform me about what I am supposed to do to finish it. It would be great if you could give me a detailed instruction before I start working on it.
Regards,
Lam.