Copyright © 2012 Bart Massey
This work is distributed under the MIT license: see the file COPYING in this distribution for license details.

These scripts, in conjunction with getmail4, will back up your Gmail account regularly via cron.

…or something. This is a very fragile and poorly tested setup, and Gmail may actually publish your Gmail password and then remove all your email, all your email backups and itself. You have been warned.

That said, I have been using Gmailbak for about a year, and it seems to work reliably for me.

1. Make a directory for your backup. It should be somewhere with sufficient storage for all your future email.

2. Create a user gmailbak with your backup directory as its home directory.

3. Make sure your backup directory is mode 700. Make a Make a subdirectory named your Gmail username. Make subdirectories of the username directory named "new", "cur" and "tmp". When you are done your setup should look like

   /storage/dir/username/new
   /storage/dir/username/cur
   /storage/dir/username/tmp
   

   Make sure all directories are owned by gmailbak. Do not make anything readable by anyone you don't want to be able to see your email.

4. Make sure you have a copy of getmail4 installed. Your distro should have it, but if not you can get a copy from http://pyropus.ca/software/getmail.

5. Set your Gmail account up for backup.

   By default, Gmailbak uses POP3 SSL, so make sure that is turned on in your Gmail settings. Make sure that the POP setting to "keep Gmail's copy in the Inbox' is turned on in the Gmail settings. Otherwise, your email will be deleted from Gmail as it is "backed up", which is probably not what you had in mind.

   If you have Google Accounts set up to do two-factor authentication, note that you will have to create an application-specific password to use POP3 SSL. This would be a good idea in any case: unfortunately you have to store your password in clear, and you don't want your general Google account to be compromised by a security problem.

   If you want to use IMAP instead of POP3 or to turn off SSL, it should be straightforward to hack up Gmailbak to do this, but I haven't tried it.

6. Copy getmail-example.conf to ~gmailbak/username.conf where "username" is your Gmail username. Edit username.conf appropriately for your connection. Again, note that this file will contain your cleartext password, so make sure it is protected appropriately: owned by gmailbak, with perms 0600.

7. Copy gmailbak.sh to ~gmailbak. Make it owned by gmailbak, with perms 0700.

8. If you want more users, you should just be able to stick more username.conf files in the gmailbak directory and add the corresponding subdirectories to your storage directory (repeating steps 3 and 6). Note that this has not been tested, however.

9. Get things started with "su - gmailbak; sh -x gmailbak.sh". You should see getmail run for a long time, then sleep for 60 seconds, then run for a long time again, until it has downloaded all the email. You can look at the log files in the gmailbak home directory or the emails themselves to verify that everything is copacetic. Note that this could literally take days.

10. Once the initial backup is done, use "crontab -e -u gmailbak" as root (or gmailbak) to insert an entry for cron to run gmailbak.sh to make your backups regularly. I use this entry to run morning and evening.

      7 5,23 *   *   *    sh $HOME/gmailbak.sh
    

• Add scripts or something to simplify the complex installation.

• Because of the one-file-per-email storage format, your backup directory may become difficult to work with due to the number of directory entries. Figure out a good plan for this.