How To Enable Offline Mode In Gmail
Just like Google Docs offline mode, Gmail too can be used in offline mode when using Chrome. In this mode, sending emails will be deferred but you can still compose emails, search and read the existing emails. Also, offline access will only be available in the regular Chrome browsing mode and not in Incognito mode.
Here is how to enable it:
Login to Gmail and click on the gear icon. Then select See...