A lot of fundraisers are very focused on this question. There’s a widespread belief that at some point, frequency of mail will cause an exodus of donors.

Thing is, I’ve never seen anything like that happen. In fact, there’s a strong correlation between increased frequency and improved donor retention. And every added appeal produces more net revenue. So why not just go for it and mail all the time?

For one thing, there’s the cost to you. Direct mail is tough work, and getting it right takes a lot of concentration and energy. Maybe too much.

Then there’s relevance: How many distinct, meaningful, relevant appeals can you make before you’re either over-repeating yourself or getting irrelevant?

For the sake of argument, let’s say you were able to mail 52 direct mail impacts a year. (I’m not recommending you do that — this is a thought experiement!)

52 appeals would produce more net revenue than one appeal. It would likely net more than 51 appeals.

But somewhere — probably well before you approached 52 appeals — you’d hit a kind of wall: Low efficiency. Appeals generally have a suppressing effect on appeals mailed before and after them. The closer they are, the stronger the suppression. So while your net increases as you add appeals, your ROI drops, eventually creeping toward break-even as your expenses rise faster than your revenue.

I’ve seen programs that were mailing 20 impacts or more a year. The net revenue was impressive. So was the donor retention. ROI wasn’t great, but it was good enough.

So how do you know when to stop?

You’re mailing too much when you over-extend your fundraising team. Those mega-mailers with 20+ impacts a year are well-staffed organizations, and they’re usually backed up by agencies to do much of the heavy lifting.

Far more organizations are under-mailing than are over-mailing. If you’re in that very large majority of mailers who send between and one and four appeals a year, seriously consider adding an extra appeal this year. It will not harm you or your donors!

(This post first appeared on July 23, 2019.)