I did vote for this one; But not because I think it is a useful product, but just the total opposite. Backup emails, is more or less as simple as backing up files. Already for years devices such as USB sticks are around to just do that. Also, many SaaS service are around that 1) keeps your files in sync between local device and cloud and optionally with other devices, 2) create backups in the cloud, or to other connected devices. Therefore, my recommendation for this product is not to spend money on it, unless you have cash to burn.
RE: Tecbasics MailBox - Mail Backup Unit