The best I've found I love the options to customize the look  the colors  dark theme. Have used for several months without one problem. I have several accounts and so easy to get all my messages in one app. UPDATE 12/3/16 I had to uninstall this app. It will only fetch and send emails for 2 out of 3 of my accounts. I downloaded a different email app and I get all my email. I wrote to the developer twice for assistance and got no reply.
December 31 2016