There are many other third-party tools available in the web market but only a few of them are reliable. I want to recommend you use the MacSonikGmail Backup tool for Mac that helps to back up Gmail mailboxes into multiple file formats like PST, PDF, MBOX, EML, MSG, etc. on Mac. This software has an amazing feature to eliminate duplicate emails during the conversion process. It is compatible with all versions of MacOS and also maintains the folder hierarchy throughout the conversion process.
