My favorite, "New donors you get through disaster fundraising will have terrible retention rates — tens of percentage points less than you're used to. That's because you get a lot of younger and less-committed donors who have no intention of ever giving again. There's not much you can do about it other than avoid throwing good money after bad.".

But read me loud and clear. Just because their retention rate is low doesn't mean you don't want their short term gift. You do.