How big a problem is shopping cart abandonment?...

According to SeeWhy, retailers who have $200 million in annual revenue may lose more than $1 million in revenue daily because of abandoned carts. Of the 20% of retailers currently employing cart abandonment campaigns, 80% say these campaigns net an open rate of at least 20%. Only about 30% of retailers report similar results from more generalized email campaigns.

It's there... go find that gold!