the winner | Postbox
None of these mail clients are bad apps, but while Mailbox is charming it’s also a bit minimalist if you’re not a paid-up Inbox Zero disciple. Thunderbird is really showing its age, and while Outlook is thoroughly excellent the need for an Office 365 subscription will rule it out for many. Unibox is a lovely thing, but if you’re used to rules and power features you may find it too simplistic; it’s a great personal email client though, and well worth £15.
That leaves Airmail and Postbox. They’re both superb apps, but of the two we think Postbox has the edge: you only need to spend a bit of time with its categories, formatting and macro creation features for it to become clear that Postbox is a powerhouse. At just £12 it’s a real bargain, too.