I recently switched from Zimbra to Outlook, and now I have a backup of my mailbox saved as a TGZ file exported from Zimbra. I am not sure how to import this TGZ file directly into Outlook 2016/2019 because Outlook doesn’t seem to support the TGZ format natively.

Can anyone please suggest an easy and reliable method or any third-party tool that can help me convert or import the TGZ file into Outlook without losing emails, contacts, and calendar data?

You'll need a trustworthy tool like Softaken Zimbra to Outlook Converter to import a TGZ file into Outlook without any issues. This software is an expert solution for user to easily converts Zimbra TGZ files into Outlook PST format with attachments. With this utility, users can flawlessly import multiple Zimbra TGZ files at once, into Outlook PST format in any huge size without limitation or data leak. Also, it ensures all original file formatting, metadata, structure, and hierarchies for backup format. There is no requirement for the Zimbra desktop installation to export TGZ data. Moreover, this application supports all major versions of the Windows operating systems.

To import a TGZ file into Outlook, you first need to convert it using a trusted tool, SameTools to Convert TGZ to PST. This software is an effortless way to convert Zimbra TGZ files into PST format without any technical issues. The tool extracts all emails, contacts, and other mailbox items from TGZ and converts them into PST format without losing data. After conversion, users can flawlessly import the TGZ file into the Outlook PST format using the built-in import option. This ensures a smooth & safe conversion process without any formatting issues. It is simple to use with friendly for both technical and non-technical users without requiring any technical expertise. Furthermore, this application is suitable for all major versions of Windows OS (new and older).
Refer: www.sametools.com/convert/tgz/