Dear [name]:
On behalf of [name of organization] I would like to thank you for your generous gift of [amount donated]. Your commitment to helping [cause] in our community is sincerely appreciated.
Each year [name of organization] continues to advance its mission of [mission]. Through our programs [name of programs] we have seen many lives changed for the better.
In particular the [program] has enjoyed great success in the past year. [details about growth or goals achieved].
The goal of the [name of organization] is to continue to make a difference in the [cause]. With the help of donations from supporters such as you we will continue to see improvements in [cause].
Thanks again for your generous support of our efforts to [what your NPO does].
source: stepbystepfundraising.com