Imagine an application that lets you effortlessly back up your gigantic Gmail account to your computer in one fell swoop; that can move your entire email history, labels and all, to a new Gmail account at the push of a button; that is completely free; that works across Windows, Mac, and Linux; that takes less than a minute to configure; and that doesn't require administrative privileges to install and use? If that sounds too good to be true, you'll be be very pleasantly surprised with Gmvault. See also: TOP 5 OFFICE SOFTWARE.
Unlike Spanning Backup, Gmvault won't back up your calendar or other Google Apps information: It's strictly for email. So far, it doesn't have is a GUI: It's a console application, and you interact with it by typing commands into a little black window. This may seem intimidating if you're not used to working in the console, but you need only a couple of commands: Sync (for backing up) and Restore (for pushing messages back into Gmail). Like Spanning Backup, Gmvault doesn't even ask you for your Gmail password: It uses OAuth, so it pops open a browser window, and you just log on to your Google account and click a button to grant it access. If you don't like OAuth, you can manually enter your password, but that method is less secure. See all: Software Downloads.
When you give Gmvault a command, it sets to work, scrolling Matrix-like log lines across the screen as it downloads your entire account, message by message. Gmvault's internal flat-file database preserves each downloaded message as two files: a metadata file, and a gz file containing a zipped copy of the message itself. Gmvault's file system is sensibly organized, and each month gets its own folder, so you can get at the messages manually using Total Commander or another file manager that handles gz files well. You can also disable compression, if you like.
Gmvault doesn't have to download your entire history: I tested it by downloading just the previous two months of email in my account. The total came to 13,546 files (from 6773 original email messages) occupying 268MB of storage space. It did get stuck once during the download, but I simply terminated the operation (by pressing Ctrl-C) and then ran the same sync command again. The download took a couple of hours on my not-very-speedy Internet connection, but it completed the job without a hitch and without interrupting my regular Gmail workflow.
Next I created a new Gmail account, and used Gmvault to "restore" (shift) the email messages to the new account, to simulate a migration. I aborted about 3 hours into the process, after becoming convinced the process works very well (I didn't really want my email to migrate to a new account). Messages uploaded without a hitch and with their original labels and other metadata perfectly intact--except for importance markers, which are not included in the process. All in all, it was a stellar performance: Gmvault worked exactly as described, and with virtually zero annoyances. The only problem I ran into was that the upload process severely congested my broadband connection, making it very slow; but you could avoid that issue by running the restore process overnight (or over several nights).
Gmvault is open-source, and the project accepts donations.