The other day, I was talking with Helen Hoart, the former marketing agent for Harvard Health newsletters, and she let me in on an interesting tidbit.Helen helped Harvard Health transition from print-only newsletters to electronic PDFs. But when it came to renewals, she used a mixed-media approach."After testing, we settled on a combination of print and online renewals even though we were serving electronic-only subscriptions," Helen wrote in an email recently. This is a very important lesson for...