I’ve found various options with Thunderbird and Mac Mail. But all require to play with the off-line or sync features. Also I needed something that I could run from the backup server without moving 25GB of email from one computer to another. After couple queries in google, I found a good solution which was using getmail to retrieve emails from POP Gmail accounts.

So, here it is. Please remember to activate POP or IMAP feature in your Gmail account settings before start.

1. Install getmail

2. Create a folder and file to store the emails

3. Create getmail folder and config file and add settings

** Please check references links below for more info about other options.

4. start backup, sit back and relax

I’m using -d here because I don’t need to keep those email account anymore. So you will need to remove it if you’re planning to continue using the account.

That’s all, add the command to a cronjob and you are all set.

References:
http://pyropus.ca/software/getmail/

http://blog.pengdeng.com/2008/03/backup-gmail-via-imap-using-getmail_16.html
http://www.mattcutts.com/blog/backup-gmail-in-linux-with-getmail/