I've also gone with Spark, after looking into the bunches of iOS mail clients. But I'm jaded now. Sparrow was independent, and good, and got bought and shuttered. Mailbox was independent and good, and got bought and shuttered. Spark is independent, and very nice, but it's free, and it'll get bought...and shuttered. :(<p>I like Google Inbox a LOT, but it doesn't have a unified mail interface, and if a million people don't use it every day, it'll probably get shuttered like Google Health and Reader did...<p>I'm just saying, don't get too attached to your email client, especially if it's not a profit center for the company making it.<p>Server-side access is what's needed in order to do push-notification based email updates, which is an important feature for me, and having written that code once or twice, I'm totally okay with that.