> If your concern are backups (only), I think there are better tools for that, such as offlineimap and mbsync.

I used to use imapbackup but I wouldn't say they are better tools:

- They rarely support OAUTH directly so it can be a pain to set up with gmail

- You still need a viewer to navigate the backup when you need it (usually a full mail client though there are some lighter maildir frontends)