If you have to use Gmail for work, there are very few, if any, reliable email clients for Windows Phone beyond MetroMail. But besides Gmail, the MetroMail app also enables Outlook and IMAP with PUSH IDLE support for instant notifications. In other words, it's quite powerful and useful for those needing an app with "100% feature-parity with the official Gmail iOS app (minus server-side drafts)", or for those who need a potent IMAP client.
Today, version 3.0 is hot off the presses. MetroMail 3.0 is so new you may not be able to find it in the Store yet. Luckily, we have the full scoop and Windows Phone 8.1 users will want to pay particular attention.
Full story from the WPCentral blog...