Dear …
Thank you for your recent order placed through __(company name)__. I just wanted to send you a note to express to you how much we appreciate your business and the opportunity to be your __(type of product/service)__ provider. Your order is currently being processed and will be out to you __(as quickly as possible/within the next (#) of weeks)__.
We want you to be able to count on us for all your __(type of product/service needs)__ and ask that you feel free to contact us at __(phone #)__ with any questions or special needs that you may have. We are here to be of service to you
Thank you for choosing __(company name)__. We look forward to having you as our valued customer for many years to come.
Sincerely,