"In Western countries, the Eastern order is generally used in lists and catalogues, with the family and given names separated with a comma (e.g. Smith, John). This convention is followed by most Western libraries, as well as on many administrative forms."
Mr Zhang San 或者 Mr San Zhang都可以。对中国有所了解的人,通常知道中国人姓名写法习惯上姓在前。关键在于你要保持统一,如果把姓放后边,那就全都放后面;如果把姓放前面,那全放前面。如果放后面的话,你可以把姓全大写,比如Mr San ZHANG,这样看信的人就可以知道哪个是姓,哪个是名。