Dear …
On behalf of __(name of organization)__, please allow me this opportunity to extend my gratitude to __(you/name of company)__ for sponsoring the __(name of event/fundraiser)__ this year. It was a tremendous success! Thanks to __(to sponsors like you in our community/your contributions/etc.)__, we managed to __(raise $amount/put on a first-class (type of event)__/etc.)__.
Everyone involved __(had a great time/is very pleased with the results)__. What a pleasure it was to see all the volunteers, participants and sponsors alike, working together to make this event the great success it was. It was a privilege for me to be part of it and I am already looking forward to next year’s __(event/fundraiser)__.
Once again, __(Name)__, thank you for your support. It was greatly appreciated by all.
Sincerely,