I'm sorry krub P'Pornchai. In my mind, If I need send email to be formal, I like to use the full name of recipients instead. Because I'm afraid all recipients will think I do not respect each person krub. But I very feel good, if P'Pornchai don't think that with me. I will remember and do that as K.Pornchai has advised me krub. Khob Khun Mak Mak Krub P'Pornchai.