Android: There are a million and one solutions to the email problem, but Boxer manages to turn some heads. The app allows you to combine all your email accounts into one inbox, turn emails into to-dos for your list, and quickly delete or archive messages.
The service is free for basic users, but if you want to add multiple accounts, you'll need to shell out $10 for Pro. That's a pretty penny, but the features of Boxer are worth it. In addition to the above, you can easily attach files from Dropbox and Box, send an email to Evernote with a single tap, and even "like" an email to reply to those messages that need to be acknowledged but don't really need to communicate anything. On the other side, your recipient will receive "Sucha Name liked your message," though, so it might only be worth using for personal email, rather than professional.
Boxer | Google Play Store via Android Police