Are you moving your MBOX file to an EML file?
FixVare MBOX to EML Converter is what I suggest you use. There is no better or safer tool for this purpose. This tool works with MBOX files from Thunderbird, Apple Mail, and Eudora, so it can meet the needs of a wide range of users. It can be used by both technical and non-technical people because it has an easy-to-use layout. This tool makes it easy to change MBOX files to EML format. People can get the free test version of this tool to see what extra features it has and learn how to use it.