I have not tried Gmvault, but I have tried two other backup solutions.
I recommend [GYB]:
- I have successfully migrated a 10+ GB gmail account to another account.
- There were a few emails that could not be restored, but I think this is a limitation of the Gmail API: it does not allow an email to be restored if it thinks it contains malicious content.
- There was also a large swath of emails that were restored with the wrong date (date of restoration instead of actual email date.) This was a little annoying and hopefully can be fixed later.
- Downsides: complicated installation and no simple way to view/search through emails.
[MailStore] is good for archiving emails (but not restoring them):
- Lacks one crucial feature: resume restore. A 10GB+ restore never works to completion on the first try, and mailstore must start over every time. So I never got it to successfully restore.
- However, it has a simple UI that allows you to search/view your emails.
[GYB]: https://github.com/GAM-team/got-your-back/wiki
[MailStore]: https://www.mailstore.com/en/products/mailstore-home/