Dear …
Congratulations on you on your__(#)__ years of service with __(Name of Organization)__. Over the years, we’ve seen you grow into a fine __(type of position)__. You are an excellent representative of our __(firm/organization/company)__ and we are very proud to have you on our __(type of)__ team.
__(Name of Organization)__ has enjoyed many successes over the years and we recognize that growth and success of any organization depends largely on its people. Therefore, I want to take this opportunity to personally thank you, __(Name)__, for the important role you have played in helping us to achieve our successes. Your dedication and __(loyalty/commitment/etc.)__ to our __(firm/organization/company)__ has been outstanding.
Congratulations again on your __(#)__ year milestone with __(Name of Organization)__. You are a real pleasure with work with and I genuinely hope that you will remain with us for many years yet to come.
Sincerely,