Today released new to the offline version of Gmail in their web browser. While offline support is nothing new for Gmail, you can no synchronize up to 31 days of mail for offline access. All attachments are also downloaded for easy access, along with full keyboard shortcut support and a variety of performance boosts. To give this new version a try, just install it via the Web Store . 

b7f4427c717979ca.jpg Google Improves Offline Gmail Support in Chrome

Link:
Google Improves Offline Gmail Support in Chrome [Chrome]