The share of email opens occurring on a mobile device keeps growing, climbing to 48 percent, according to a 2015 report from Litmus. Given the rapid growth in mobile email opens, it's only a matter of time before more than half of total opens will occur on a mobile device. Marketers face a real challenge in finding ways to market effectively on increasingly shrinking screens. Savvy marketers know they need to think about how their email marketing is affected by this trend. Now, we're not just worrying about overcoming spam filters, we also need to consider how and where an email will be viewed, when it will be relevant, what action will need to be taken and on what device?