1.
Dear Sir,
It has been such a long time since our last contaction. How are you ?
2.
Dear sir/ madam:
He a nice day. we hen't contacted with each other for a long time.How are you these days?
3.
Dear Sir or Madam,
It's greeting from xxx from xxx company, China, we didnot hear from you for some days and hope everything is fine with you
4.
Dear,
How are you? Hope everything is ok with you all along.
Now I am writing for keeping in touch with you for further[收起]