EML file is a file format produced by Microsoft Outlook. EML file is an drafted or archived email that preserves the original format of HTML include headers. Almost email clients support this file format, such as thunderbird by mozilla developer.
You can also open EML files using web browser, but you must rename the eml file to *.mht . because EML files is similar to MHTML that .MHT can be opened in microsoft edge. just right click on dot eml files and choose rename .eml to .mht.