Return Path, an email certification company, said ecommerce site Groupon, which offers a daily deal on local goods, services and events in more than 500 markets worldwide, earned a 40% increase in
delivery speed and increased email response rates with Return Path's Certification. It also saw 2% better open rates and 6% better click-through rates for those emails being sent over the Certified
IP. Limited-time offers are sent daily to Groupon's list of more than 70 million subscribers, targeted to geographic locale and subscriber preferences.