I've written about my attempts to find the right mail app before. When Mailbox was shuttered it left a lot of people scrambling for a replacement; I settled on Edison Mail (originally called simply Email by EasilyDo) while on the iPhone and still use it now I'm on Android.
Seeing that Edison are now launching a fully fledged mail service called OnMail caught my eye. They repeat the mantra that "Email is broken" and "the email services we’ve known and loved don’t seem to be cutting it anymore". Having spent a number of years working on their own app they claim to be "uniquely poised to fix the issues surrounding email" but how many times have we heard that before!
Still, having used there app for this long I'm willing to give them a chance and have signed up to their waiting list in true Mailbox style (remember those days?) They also give you a referral code to pass on to others so you can use that if you're as curious as I am.