Fully 67% of marketers said email list growth was very important to the overall success of their marketing program.
Open rate was far and away the most common metric for determining the best subject line, used by around eight in 10 marketers.
Click-to-open rate dropped 9.6% year over year, and transaction-to-click rate fell 15.6%.
Travel & leisure registered a particularly high unsubscribe rate, which rose to 6.77% in the bottom quartile. Computer software was again a top performer, though nonprofits recorded the lowest average.