By default, no. But you can easily enable it. At least for mail/calendar/contacts. https://www.eff.org/deeplinks/2013/01/yahoo-mail-makes-https-available https

By default, no. But you can easily enable it. At least for mail/calendar/contacts. https://www.eff.org/deeplinks/2013/01/yahoo-mail-makes-https-available https://www.eff.org/deeplinks/2013/01/yahoo-mail-makes-https...