Sparrow announced late last week that it had been acquired by Google. In its announcement, the company said it will continue to make both the Mac and iOS versions of the Sparrow email client available and provide support for its customers. This means that iPhone owners can continue to use the current version of Sparrow, but at some point, iOS is going to outpace the app and you're going to need to switch to a different email client.
If you're on the hunt for a new email app, then you should check out some of the iOS email clients listed below. If you have a favorite that's not included below, please share it in the comments. Mac users may also want to take a look at our list of email clients for the Mac.
Default Mail app for iOS (Free)
For most users, the default iOS email app is sufficient. It supports a variety of accounts including IMAP, POP3, Exchange and services like Hotmail and Yahoo!. It's a basic email client that'll alert you when you get an incoming email and will let you move, delete or flag a message as important. You can setup an email account for push, if supported by the back end, or set the client to check your email at regular intervals. There's also a handful of options that'll let you select your default account, tweak how many messages you view, setup a custom signature and more.
The Gmail app is for heavy Gmail users with a single Gmail account who need access to Google-specific functions like labels and the priority inbox. Besides labels, you can also archive and star emails. All changes made in the mobile client will be reflected in the web client. The latest version adds support for the iOS Notification center and lets you send an email using an alternative email address, if it's been configured within the Gmail web client settings ahead of time. The Gmail app is a universal app that works on the iPhone and iPad.
iMailG - Gmail and Google Apps on the go (Free, in-app purchases)
iMailG lets you manage your Gmail as well as the other Google services within one app. It works well for iOS owners who use the full suite of Google Apps including G+ and Google Calendar. Multiple sign-in is supported, but that has to be turned on for each Gmail account first.
The app is available for free, and a series of in-app purchases will unlock specific functions like push notifications (provided by a third-party service). It's a little heavy on the in-app purchases, but it might appeal to some Google users. There's also an HD version for $1.99 that's optimized for the iPad.
eMailGanizer Pro ($4.99)
eMailGanizer is a mail app that'll help you control your deluge of incoming emails by making it easy for you file them into folders quickly. You can also add emails directly to your iPhone calendar or add them as tasks to outside sources like Toodledo, OmniFocus, Things, The Hit List and more. eMailGanizer works with multiple email accounts and supports IMAP, Exchange and third-party services like Hotmail, AOL and iCloud. It takes a while to add each email address and set up the folders, but it's a very useful system once you've got it up and running.