Dear Sales Manager or Concerned Person.
Recently our cooperation contract was just finished so I apologize that I did not contact you earlier. However, our business should be kept going so I would like to extend our business contract for 1 year further. After you read this email then you should recognize I have already called to confirm the name of email receiver (It means this email was opened by your side).
If you would like to change whether prices and products details please inform us by this email within 30 days after you received it. If I have no reply from you after 30 days I will assume that you have ignored to change any prices and product details and I will 1 year extend our former business contract automatically.
Thank you for your cooperation.