厂长夫人，你好，收到此信息你一定会惊讶吧！

Madame of the head of the factory, hello, you must be surprised when you receive this message!

Hello,Mrs..(厂长的姓)(外国人一般不会用称谓加夫人)
You must be very surprised to this letter.

Hello,Mrs……
You must be very surprised to receive this meseage.