I am in the process of switching our email system to Zimbra, and I have run into a problem. I have a large number of MBOX files that I need to import into Zimbra, but Zimbra only supports TGZ format for mailbox import. I have tried looking for manual methods, but I could not find a straightforward or reliable way to convert MBOX to TGZ without data loss. Some files also contain important attachments that I do not want to lose during the migration. Can anyone guide me on how to properly convert MBOX files into TGZ format for Zimbra?