The simplest way to inspect, search, and recover your email archives on macOS.
An MBOX file is a universal email format that bundles messages into a single file. It's the standard for Gmail Takeout, Apple Mail exports, and professional backups.
Ensure your file ends in .mbox. Some exports lack an extension; adding it manually can help.
For best performance, move files out of iCloud, Dropbox, or network drives onto your local Desktop.
Ensure you have at least 2x the file size in free space for temporary indexing and processing.