Dear Sirs,

It would be a great help for me if u people send me some specimens of letter of thanks after receiving a successful business deal from a client (insured)

Regards,

Asif Noor

Well, if there are any women that will receive the letter, I would suggest starting with "Dear Sir/Madam."

Are you asking to help drafting a thank-you letter for someone doing business with you? I'm not clear exactly. Or did they refer new business to you?

By the way, I'm a "madam" but I'm sure I can help you. :)