> Yahoo Mail is an underdog too: It represents 6.3 percent of email clients, versus Apple’s 43.6 percent, Google’s 30.3 percent, and Microsoft’s 11.4 percent

When I read this I thought this Apple's 40%+ email share can't possibly be true and I read the linked article and realized if an iPhone user is reading their yahoo.com or hotmail.com email on the Mail app on their phone, it counts as an "iPhone email", so this number is meaningless, although it's probably true that Yahoo email has a smaller share than Hotmail or Gmail.