EML file is basically a file extension of email messages which are received or sent through POP3 email application. Usually this .eml file format is associated with Microsoft Outlook Express which is also a POP3 email client application developed by Microsoft. Apart from Outlook Express, EML files are also created under several other email clients like Windows Live Mail, Thunderbird, IncrediMail, etc. They all follow MIME RFC 822 standard format that specifies distinct parts of an email like images, html, attachments etc. EML files are usually saved in plain text format.
If you only want to view or read content of EML file, then you can open it with Notepad or any other word processor but If you want to read content of EML file with proper formatting and attachments then in such situation you can try Free EML viewer utility which is a freeware tool to open and read multiple EML files without any platform dependency.
You can get detailed information here –