未婚用Miss
未知对方结婚与否时用M.S
外国人名字前面加M/S一般是Madam or Sir（先生/女士），用于书信往来时暂时不清楚对方是男是女的情况。
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书信
像印度等非英语母语国家，在商务信函的开头 对方公司前面一般也习惯加M/S，如
to Reliance industries （致：信实工业）。
这里的M/S是法语Messers的缩写，相当于对客户的尊称，类似于中国古代 XX商号。
具体资料如下：
M/S is short for Messrs which is the plural for Mr in French. The term M/S is generally placed before the names of partnership firms to indicate that it is firm comprising several partners and is not a sole proprietorship. For instance, M/S Batliwala & Co (there are partners other than Batliwala in the firm of Baltiwala & Co). In India, the term is also sometimes mistakenly used in the names of joint-stock companies such as for example M/S Reliance Industries Limited. This is not correct since a joint stock company under law is an artificial person by itself; but looks like the practise has caught on.
M/s is use for company because in law company is a person it has all the right which has a man. Like a person born company also born and as a person died a comapny also died. Compnay has its own identity and have so may rights. So that like we use a man/women mr.mrs, or miss for giving them respect same as we use m/s for company.
M/s stands for 'Messrs' ('Messieurs' in français) which is literally plural of Mr .