Do a backup `<account>` elements are required when `method=full` and server is running in standard backup mode. If server is running in auto-grouped backup mode, omit the account list in full backup request to trigger auto-grouped backup. If account list is specified, only those accounts will be backed up.
Full documentation: https://files.zimbra.com/docs/soap_api/8.7.0/api-reference/zimbraAdmin/Backup.html
The first param is the `Mailbox Server`. You need direct access to the `7071` port on this server.
Get All Volumes from the server. [This link](https://files.zimbra.com/docs/soap_api/8.7.0/api-reference/zimbraAdmin/GetAllVolumes.html) has full documentation