An EML is a file extension for an e-mail message saved to a file in the MIME RFC 822 standard format supported by Outlook, Outlook Express, Windows Live Mail, or Thunderbird. Furthermore, the EML file format is a plaintext MIME (rfc822) file format for storing emails. On the other end, MSG is a compound file binary format based on Microsoft’s Outlook MAPI. Also, the Outlook Item MSG (. msg) file format is a syntax for storing a single Message object, such as an email, an appointment, a contact, a task, and so on, in a file.