After spending about six hours (and losing several pounds due to fever-level frustration) working on this problem, I believe I have finally figured out how to perform something resembling methodical eDiscovery for Gmail emails if you, like me, work on a Mac. You will need the following:
2. Google Vault (this software, truly, is spectacularly bad)
3. Stuffit Expander (yes, seriously, like that one from 1997)
4. Mac Mail
5. Acrobat Pro XI
1. Enable Google Vault for whatever email accounts in which you need to perform your production queries.
2. Perform your queries.
3. Use Google Vault's incredibly ham-fisted "export" function for each of your queries.
4. Serially download each of the multiple mbox.zip files that result from your exports.
6. Unzip them with Stuffit Expander (for some unholy reason surely only known to Cthulu and other eldritch gods, Google has chosen to use pkzip, instead of you know, just freaking zip, so your OS will think the files are corrupt unless you download Stuffit Expander, a piece of software old enough it can vote).
6. Serially import each of the mbox files into Mac Mail.
7. Select all the contents of each mbox import folder, one at a time, in Mac Mail, and print them to .pdfs.
8. Now is the time to remove emails that you do not wish to produce for reasons of relevance or privilege. Google Vault simply does not have anything remotely resembling this function: you either export the entire results of a query in a single .zip, or nothing at all. Thanks, Google Vault. Further note, however, if you are not careful in this process, you may be running afoul of your requirements for privilege logging. While sorting these results, it is best to keep a separate folder for emails that you determine to be relevant, but privileged, in order to preserve them for future examination.
8. When you have all your .pdfs collected in a folder, open up Acrobat and use the "Bates Numbering" function in View -> Tools -> Pages (intuitive, right?) and assign Bates numbers.
9. Drag the files to a thumb drive.
10. Send the thumb drive to opposing counsel.
11. Curse every piece of software you had to use in this process for being ungainly, cumbersome, semi-functional and poorly designed for this purpose (note: except Stuffit Expander. It had one job and did it without any fuss, complaints or troubleshooting).
And people wonder why lawyers are always angry.