Dear …
Once again I thank you for your business and the confidence you have placed in me at __(company name)__. It’s clients like you, __(name)__, who make my job so enjoyable. I can’t tell you what a privilege it has been for me to be able to provide you with all your __(type of service/product)__needs over the past __(#)__ __(months/years)__. Your continued loyalty is so greatly appreciated. It gives such a strong testimony to me to the kind of service that __(I/we)__ truly endeavor to provide.
Thank you again, __(name)__, for continuing to put your trust in __(us/me/company name)__ as your __(type of position)__. It has been an honor for me to be of service to you and I genuinely look forward to working with you for many years to come.
Sincerely yours,