The GMail for Android app has been updated and users who are running Android 4.1 Jelly Bean or higher will have the ability to interact with GMail notifications directly from the notifications panel. That means you can choose to reply, archive or delete an email from your notifications before even having to open an app. GMail for Android allows you to keep your conversations going everywhere you go. You can get access to your GMail account instantly through push notifications, read and respond to your conversations or search and find any email.
You can download the update directly on your device through the Google Play Store or by using the link which follows:
Additionally the update will allow users to customize which messages you receive notifications from and set custom notifications for certain messages.
The update will also be available for Android 4.0 Ice Cream Sandwich users but it will only bring performance improvements and bug fixes. Additionally you will get faster search and improved search suggestions so you can find messages quickly whether you're online or offline. Other versions of Android which will receive the GMail update will also notice performance improvements.
source - Google