Can you help me for a minute ?   Sure , what I can do for you ?   I'm try to write a letter to one of our clients , But I just don't know exactly what to say , I don't even know how to get started , I know I should write dear Mr . Mrs . or Ms . , but the problem is I don't know the name of contact person .   You can just put Dear Sir or Madam , officialese not personal , you can write to whom may concerned .   OK , So I first thanks them for their business , I can say something like we are very grateful for your continue support , How is that ?   Good ! But also , write off the bed you want to tell them the reason of your writing , give them more reference . 