An EMLX file contains an individual email message created by Apple Mail, an email program bundled with macOS.
It stores the contents of a message, which includes the subject, sender, and recipient. EMLX files do not store email attachments, only the message information.
EMLX file open in Apple Mail 8
EMLX files created by Apple Mail are not meant to be manually opened. However, if you encounter an EMLX file, you can double-click it to open it as long as Apple Mail is set as the default program.
Since the EMLX files are saved in plain text, you can also open the file to view the contents in a text editor, such as Apple TextEdit or Microsoft Notepad. You may need to change the .emlx file extension to .txt.
When an EMLX file is created by Apple Mail, the file is typically saved in one of the following folders: