Using Forwarding or POP option:
You can simply create a backup of the emails you have received so far by using the forwarding option in your Gmail account which is found in the settings option in the gear menu on the top right hand corner of your Gmail account window. Using this option, all your emails will be downloaded to your specified desktop software.
If you want to take a backup of the mails you have sent so far, use POP option which is found in the settings of the gear menu. Enable POP after selecting the Forwarding and POP/IMAP option and configure the email client according to your requirements.
Fetchmail:Licensed under General Public License, this is a free Gmail email backup utility which downloads emails from IMAP and POP remote servers so that they can be saved and available on the local mailboxes. In order to install fetchmail follow the details at fetchmail.com.
Gmail Keeper: This is yet another utility that is meant for paid windows and keeps a local copy of your Gmail mails. Visit gmailkeeper.com for further information on how to create a backup.
Backupify: Backupify is a very exciting utility equipped with different features for cloud based data, that provides archiving, searching and restoring the services like Gmail. You need to have one account that will not only access the information on all the accounts but also creates a backup. For backup follow the process at backupify.com .