The foremost step is to download and install Zimbra to MHTML Converter on your Windows system.
Click on the Browse button and add Zimbra TGZ files.
Get a complete display of Zimbra files before the conversion. Also, choose selected Zimbra items to export.
Pick MHTML file format in Export options.
Use the Browse button and mention the location of your system to save MHTML files.
To finalize the conversion, click on the Generate Now button.