The practical way to import Zimbra to Thunderbird on Windows 11 is to first convert the Zimbra mailbox stored in TGZ format into MBOX format. Thunderbird cannot read TGZ files, so converting them into MBOX makes the mailbox compatible with the email client. Many users rely on tools like SysInfo Zimbra Converter because it helps convert TGZ files to MBOX while keeping important data such as attachments, email headers, and folder hierarchy unchanged. The process typically involves adding the TGZ file to the tool, selecting MBOX as the output format, and starting the conversion. Once the file is converted, you can import the MBOX file into Thunderbird on Windows 11 and access all your Zimbra emails without data loss.