Yes

Is Direct Mail Dead? - Philanthropy.com:

"'The economics of direct mail are failing,' writes Mark Rovner, a fund-raising consultant on the blog Sea Change Strategies. 'That is more or less an uncontroverted fact It costs more to mail, and fewer new donors come back with each mailing. This trend has been masked somewhat by higher average gifts by donors you already have, but sooner or later, the acquisition crisis is going to affect bottom lines. For some, it already has.'"