This is possible via the Google Apps Email Audit API[1], which is accessibly only by paid Google Apps accounts. The API submitted export request takes usually several hours to complete and results in a series of large mbox files (1 GB chunks I think) containing the entire mailbox, including trash (if requested). However some meta information such as labels/folders is not present, but the results can easily be concatenated into a single mbox file containing the entire contents of a Google Apps email account.

[1] http://code.google.com/googleapps/domain/audit/docs/1.0/audi...

Thanks for that. Weird that it's a buried feature.

Seems like "easy self-directed backups" would be a nice selling point.

Shouldn't that be possible via IMAP?

Yes, it is possible

It should be easier than that.

POP? It's leaner.

Seriously, it's an absolutely perfect match for exporting everything, and it's easy to set up, and you get it in the format of your choice. Infinitely easier than having them support only formats they have time to write exporters for. It's also easily resumable, unlike the 8GB zip file I'd otherwise have to download.

You do realize that POP only supports your Inbox, right? The protocol has no concept of 'folders' or 'tags.'

I think if you switch it to "all mail", it downloads everything. Though you might be right.

POP might be a start, though for a proper backup tags need to be included somehow, maybe in a custom header field.

IMAP can be used to download the raw message bodies. hierarchical structure (aka threading) comes from the parsing of Message-ID, References, In-Reply-To MIME headers contained in the bodies.

So only download the All Mail folder into a single mbox.

Then you miss the tagging information.

I'm confused. How does a single large mbox file of all emails in a GMail account map directly to GMail's structure? That's the the OP was asking for.