How do I convert EML to the MBOX file?

[michaelwilson]

If you want to convert EML to MBOX files, then  I  would suggest a professional tool like Sametools EML to PST Converter.  It can convert bulk EML files into MBOX format. The utility supports many MBOX-based email programs such as Thunderbird, The Bat!, Eudora, Netscape, Spicebird, Entourage, and others. During the conversion process, the utility also maintains the entire folder hierarchy and organization.  There is no file size restriction; you may easily convert any large-sized EML files into MBOX format without any data loss. You can test out its free trial version and see how this program works. 

Read More: https://www.sametools.com/convert/eml/