I&#x27;ve been using Postbox since 2012. It&#x27;s a great client and while I&#x27;ve tried a ton of others (Apple Mail, Thunderbird, AirMail, Sparrow, Dropbox Mailbox, etc), I always come back to PostBox. It&#x27;s stable, simple, has access to some Thunderbird extensions, and just works like I need it to.<p>My only gripes are that development is inconsistent at best (v4 took far too long to come out, in my opinion) and they seem to focus on features that don&#x27;t add much value to the client. But overall, it&#x27;s a great client that I was more than happy to pay for.