Forty-eight percent of emails were opened on mobile devices during Q3 & Q4 last year, according to a new report from digital marketing firm Knotice. For the report, the company measured the mobile activity of email marketing campaigns during 2013 based on a sampling of 500 million emails sent across 11 industry segments. Mobile opens rose during the year. In Q1 & Q2 2013, mobile email opens only reached 48 percent.