Good thank you letters are an incredibly important and savvy marketing and fundraising strategy. Why? Because so many nonprofits do a terrible job with them. By expressing your gratitude frequently, on time, and in a personal way, you will rise above many other nonprofits in your supporters' hearts and minds.
20 Dos and Don'ts for Nonprofit Thank You Letters
How to Write a Nonprofit Thank You Letter
I devoted an entire chapter of her book, The Nonprofit Marketing Guide: High-Impact, Low-Cost Ways to Build Support for Your Good Cause (Amazon) to thank yous. See Chapter 11, "Adopt an Attitude of Gratitude." (It's a fitting place in the book, since without good thank-yous, you could end up facing your own version of Chapter 11 bankruptcy!)
Several times a year I teach a webinar called Writing Thank-You Notes That Inspire Future Gifts for CharityHowTo.com. You can attend for free if you are an All-Access Pass Holder or register through CharityHowTo.com. If it's not currently on the schedule, the most recent recording is most likely available in the recording archive for All-Access Pass Holders.
I've also written several articles you'll find helpful:
Examples of Great Nonprofit Thank Yous
(For more on how Epic Change has built its entire fundraising strategy around gratitude, read their blog.)
The Thank-You Experiment
At the end of 2008 and 2009, I gave online donations via a giving portal to about a dozen national nonprofits (I cashed in miles with Capital One, who partners with Network for Good for charitable giving). My original intent was to analyze the followup communications provided after an unsolicited online gift, but the response was so underwhelming that it turned into an experiment on thank you notes.
I am repeating the experiment now, with 20 year-end gifts made on December 30, 2011.
Here are the related posts:
After the December 2008 Gifts
After the December 2009 Gifts
After the December 2011 Gifts
Additional Thank You Letter Resources
The November 2011 edition of the Nonprofit Blog Carnival, hosted by Pamela Grow, focused on thank you letters. You'll find links to lots of great advice and examples.
Here are a few of my personal favorites from the round-up:
When Saying Thank You is an Art, Not a Process (Good real-world examples of what to say -- and not)
3 Simple & Impactful Ways to Thank (and Steward) Your Donors (Getting your system in place)
7 Ways to Say Thanks (More easy ways to build gratitude into your work)
The Thank You Letter Clinic at SOFII (More good examples)
How to Thank Your Foundation Funders (it's a little different than individual donors)
Here are lots of other articles on writing thank yous that I've bookmarked for you.