Back Up Your Email-Google

To back up all your Gmail emails—just in case!—you can install the free email client Mozilla Thunderbird (or another similar program), download all your messages, and then back up the file that contains all your email. You can then burn this file onto a CD, DVD, or copy it to a hard drive—anywhere where you can keep it safe. Then you can restore it at any time, even if you've deleted the messages in Gmail, or even if you no longer have the Gmail account. Here are the steps involved:

1. Activate POP in Gmail
For this hack to work, you need to activate POP in your Gmail. POP is short for Post Office Protocol, and it's a standard way to retrieve messages from an email server. Go to Gmail and click Settings
Forwarding and POP. 

Check the "Enable POP for all mail" box and save your changes. You are now ready to access your Gmail messages with a desktop client, such as Thunderbird.

2. Install and run Thunderbird
To install Mozilla Thunderbird, point your browser to http://mozilla.com/thunderbird/ and click the Download Thunderbird button. You will be asked to save an executable file on your disk. Run the installer and complete the setup.

Now start the Thunderbird program. During launch, you will be guided through an account wizard where you provide your Gmail credentials. Just choose Google Mail or Gmail from the list of selections and enter your name and email address in the dialog