To eliminate duplicate emails from MBOX files, you can either use a manual method or a professional solution. Manually, you can import the MBOX file into Mozilla Thunderbird and use filters or add-ons to find and remove duplicates based on criteria like subject, sender, or date, but this process is time-consuming and not always accurate. A more reliable approach is to use a dedicated tool like SysTools MBOX Duplicate Remover, which can automatically scan and remove duplicate emails from single or multiple MBOX files using advanced parameters while preserving data integrity, making it the most efficient option for bulk and secure cleanup.