This is something I know will excite many people. Google is gearing up to handle all of your email accounts with Gmail (for Android). From what I am reading you will be able to setup Gmail (when the new version is released) to pull in mail from other external accounts you may have (such as Outlook and Yahoo).
…the new Gmail will be able to handle email accounts from other providers like Yahoo or Outlook, switching between them with either a simple swipe or by touching the account drop down. Here’s the new onboarding video Gmail will show for returning users upgrading to the new version. Source: Android Police