>> Login to your Gmail account with Standard View.
>> Click on Setting then click on Labs tab. Select "Enable" for offline Gmail and click on "Save Change" button. Gmail will be automatically reloaded and after that you will have a link "Offline" left side of "Settiong" link on right-top corner
>> Now install Gears clicking here for your browser. After completion of Gear Installation. Click on the "Ofline" link on your Gmail homepage as I previously mentioned.
>> After click, you will have a dialog box, click on "Install".
>> After that mail files will be downloaded on your Computer.
>> Now enjoy accessing your Gmail Inbox in offline without Internet Connection just clicking on Gmail Icon on your Desktop