There are two types of direct mail fundraising: house-file and prospecting. House-file mail is the mail you send to your current donors – those who have already contributed to your organization at one time or another.

As you try to raise funds effectively, it is important to cultivate your relationship with your supporters, the ones who already like the work that you’re doing and are invested in your success. One of the most powerful tools at your disposal is house-file direct mail.

When you write to your donors, you have two aims. The first is to keep them connected to the mission of your organization; the second, to bring in the money that allows your organization to do its work.

These goals are essentially the same. That is, if you are keeping your donors engaged with your mission and your work, it’s sure to show in the contributions that they send in. Or put another way, because they’ve given before, you know that your donors are aware of the work you do and want you to keep doing it. The role of direct mail, then, is simple: To make sure it stays that way.

Follow these steps to write copy that is compelling and will keep your donors supporting your organization—morally and financially—for years (and even decades!) to come:

(1) Write 3-5 pages for each appeal.

Research has shown that longer copy yields better results. Be sure to say everything you need to say and don’t limit yourself to one or two pages because “who would read anything longer than that?” The fact is that people like to be involved in the lives of the organizations they support. Now, it’s true that because these individuals are active donors, you will not need an introduction—and therefore a longer letter. Copy of 8+ pages should be reserved for prospects who know nothing (or very little) about you. Four pages or thereabouts is a great length for house-file copy.

(2) Thank your donors for giving in the past.

Throughout the letter—but especially in the beginning and at the end—remind them of how important their contributions have been for your work. Let them know that without their support, the good work that your organization is doing would not be possible.

(3) Restate your mission again and again.

Don’t get caught in the latest developments that affect your work. Of course it’s important to refer to what’s happening in the world and to talk about your most recent initiative (even in detail), but don’t let that drive your letter. Your identity is not reducible to one aspect of your work. Instead, let any particulars you share support your overarching narrative: “This is who we are; this is the work you want to continue to support.”

(4) Tell a story.

Have you ever seen how certain children’s charities connect donors to the kids their monthly $24 is helping? Some of these groups even have the kids write their letters to their “sponsors.” It makes sense—donors love to see the real-life effects of their contributions. They are proud to be taking part in something bigger than themselves that changes the world for the better. Telling particular stories is simply an excellent way to show your shared universal values in action.