You can easily do it by adding the complete folder which includes EML files. This way, the execution can be faster because you need to load all the files at the same time rather than loading EML data one after another.
This tool provides the preview of emails in different advanced modes. You can view the emails in modes like Property, Hex, HTML, MIME, RTF and Message Header.
So This Regain Software supports both EML & EMLX files (Mac OS X email format), Try latest version EML to PST Converter tool which now supports both 32 bit and 64 bit of Microsoft Outlook.
You can try its Free Trail Demo Version and evaluate the software completely. The trial version allows saving only 15 items of each folder of the mailbox which is converted by you.