got-your-back uses Gmail's API instead of IMAP with an insecure app password, which is a discouraged way of accessing Gmail and will eventually be phased out in favor of OAuth access tokens over IMAP (in fact, I thought it already had been).<p>As for other services beyond Gmail, there's not a great ecosystem for exporting.<p>For one-off exports, Google Takeout is decent enough, although there's a lacking ecosystem to import the big .mbox files back to an email provider.
Nice but... Backup is nothing without restore and actually "restore" for third party services on a closed proprietary infra it's not possible...<p>My way for mails is simply having local maildirs using mails via notmuch and serving the maildir if needed via local dovecot/with an eventual MailPile/Rainloop etc webmails, for contacts Davis (like Radicale or Baikal) with DavX⁵ on Android etc, IOW the sole way I fond is being able to use someone else service if I need it (for instance not to end up in spam on all web giants mails) but still owning my infra. Just having data I can't really use it's not enough unfortunately...