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. :(

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...

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.

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.

After Mailbox announced it's being EOL'd, I needed a replacement mail app with similar features (snooze, specifically), and I decided to give Spark a shot. That was after trying a plethora of other mail apps that many news outlets recommended as Mailbox replacements. I gotta say, I wish I knew about Spark sooner! It's way better than Mailbox, and it's by far my favorite mail app ever. I love the direction the app is going, and the fact that it's seen elevated development since the Mailbox announcement. I recommend this to anyone who uses email.

It's more powerful and customizable than Mailbox. Most importantly, it doesn't have server side access to your email or email account! I left Mailbox a while back for that reason and for lack of IMAP support.

I actually regret not switching to Spark sooner, since it has support for more email providers than Mailbox ever had. I do wish it would take some cues from Inbox and add the Action support, though.