Here’s an A/B test we did..
A random set of customers, who have been inactive since the past 6 months were selected. A letter was drafted, that talked a about how we’ve improved in the last 6 months and a personalized coupon code was included with the letter to incentivize them to give us one more shot. This letter was delivered via email to one half (of the inactive set) and via snail mail to the other half.
We decided to measure the efficacy by seeing how many people actually ended up shopping using the coupon codes sent. The result was counter-intuitive to me – snail mail converted 5x better.
Is it just the amount of spam that people receive everyday, rendering email much less effective (or attention grabbing) than receiving an old fashion letter? Perhaps it is Gmail’s new tabbed interface to blame to some extent.. we have seen our open rates go down since.