Usually, the default mail app on Android phones is capable but lacks email management. Mailbox, a free email app from Dropbox, offers smart management features for email along with a great user interface. The main window displays your emails in a list along with a two line preview — useful to identify important mails. It also lets you clean your inbox by giving you the option to archive mails (keep unread or starred mails in the inbox and archive the rest). Another helpful feature is the option to set reminders — you can have the app remind you about things to do regarding individual emails. The only issue is that it only works with Gmail or iCloud Mail at the moment.
