If you are looking for a manual method to import EML into Outlook, you can read this blog. But, manual processes have several limitations, so I recommend you can use the third-party EML File Converter. It is one of the most efficient and dependable tool to convert mailbox data from EML files to Outlook PST files. The software entitles users to convert EML files to various file formats such as EMLX, HTML, PDF, MSG, PST, etc. It can also export EML to Gmail, Yahoo, Outlook, IMAP, Thunderbird, etc. Although, it offers a free trial version to test its efficiency. The utility works with both Windows and Mac OS editions.