[Your letterhead, if desired; if not, your return address]
[Date of letter-month, day, and year]
[Recipient's first and last names]
[Street or P.O. box address]
[City, State ZIP code]
Dear [recipient's name]:
We are writing to you in response to the email that you sent to us on May 18, 2010. Thank you for contacting us with your suggestions, which were all excellent. As you may know, we truly appreciate customer feedback and consider our customers to be more than customers, but rather partners with us. Customer suggestions such as yours make our company and its products truly great. So thank you for contacting us and sharing your ideas.
If you have additional comments in the future, please do not hesitate to send them along to us. We will be happy to hear and consider them. Thank you for being such a loyal customer and for contributing such valuable ideas.
[Sender's first and last names]