In 3Q14, some 17% of all subscribers to brands' email programs were using Gmail. That percentage increased to 30% in 3Q17. Some 49% of consumers who opted into marketers' email programs in the previous 90 days use Gmail. That's compared with 15% who use Yahoo, 8% who use Hotmail/Outlook, 3% who use AOL, and 26% who use other ISPs. Get the full story at MarketingProfs.com