The average email subscriber gets 416 commercial messages per month, says Return Path, and that number may just get higher. The latest quarterly email benchmark study from Experian Marketing Services indicates that email volume grew by 17.9% year-over-year in Q2. That follows an 11.6% increase in Q1, a relatively modest 5.4% bump in Q4, and no change in Q3 2012. Open rates don’t seem to have suffered, though, with total and unique open rates up year-over-year during Q2. Read the rest at MarketingCharts.