Convert Outlook Emails from .Msg to .Eml Files

An illustration of an email viewer. On a laptop, an envelope and @ symbol appear over an illustration of the earth.

EML Viewer Pro (also known as PstViewer Pro or MailDex) is a  versatile Windows software app. You can use it to manage, search and view emails that are formatted in a variety of common formats, including .EML, .MSG, .MHT, .PST,  .OST and .OLM files.

One of the nice features of EML Viewer Pro is its ability to convert and export email messages from one format to another.  With the latest release, you can now export email message content to .EML format. .EML files are formatted according to the RFC-822 spec. As an open format, it is supported by most email clients, including Windows Mail and Mozilla Thunderbird.  Because it is an open, non-proprietary format it may be useful to convert emails into .EML files for purposes of email archiving, long term preservation or sharing.

Here’s how to convert Outlook .Msg files into .EML files using EML Viewer Pro.

First, open EML Viewer Pro, and find the folder containing your Outlook .msg files.   Click on the folder, and EML Viewer Pro will read in the msg files and display them in the main list.  Select any listed email message to view it in the reading pane. Double click on an email to open it in full screen view.

Select the emails you want to convert into .EML files.  To select a message, you click on it.  To select multiple messages, hold down the control key, and click on the messages you want.  To choose all of the emails in the list, type Control-A on your Windows keyboard.  Messages that are selected are shown in the list with a blue highlight.

Picture of EML Viewer Pro main menu with msg files selected.
Eml Viewer Pro main screen. Selected email messages are highlighted blue.

When you have selected the emails, you can export them in a single batch operation.  Choose “Export to EML” profile from the toolbar drop down list.

Picture shows how to select the "Export to EML" export profile in EML Viewer PRo
Choose the “Export to EML” profile

To begin the conversion process, click the Export button (the icon with the yellow paper and the green arrow).  EML Viewer Pro will go to work exporting your .msg files to .eml files.

Export process progress bar
Exporting msg files to eml

There is no limit to the number of messages you can export (note: if you are using EML Viewer Pro in trial mode, the limit is 50 emails per export operation. This is removed after the software is purchased).

If you need an flexible tool to help manage your email content, try EML Viewer Pro. It’s several tools in one: view, search, and export.  You can download a free trial and learn more about EML Viewer Pro from the product website.

Viewing and Understanding Email Internet Transport Headers in .EML Files

A screen shot of Pst Viewer Pro displaying email internet header info.


An EML (Electronic Mail) file is an open file format used to store individual email messages. It is a standard file format often associated with email clients like Thunderbird that follow the MIME (Multipurpose Internet Mail Extensions) standard. EML files contain the complete content of an email message, including the text, attachments, and metadata.

An email internet transport header, also known as an email header or message header, is a block of metadata information that provides details about the origin, route, and content of an email message. This information is not typically visible in the body of the email when you read it but can be viewed by accessing the email’s header section.

Email internet headers are usually not visible to users. A useful tool for managing EML files and viewing the internet header is a Pst Viewer Pro (formerly known as EML Viewer Pro) by Encryptomatic LLC, a U.S. based software developer.

Here are some key components typically found in an email internet header:

  1. Return-Path:
  • The email address to which bounce notifications and delivery errors are sent.
  1. Received:
  • This section contains information about the servers through which the email passed on its way to the recipient. It includes details like the server’s IP address, timestamp, and authentication information.
  1. From:
  • The email address of the sender.
  1. To:
  • The email address of the recipient.
  1. Subject:
  • The subject line of the email.
  1. Date:
  • The timestamp indicating when the email was sent.
  1. Message-ID:
  • A unique identifier assigned to the email for tracking and reference purposes.
  1. MIME-Version:
  • The version of the Multipurpose Internet Mail Extensions (MIME) standard used in the email. MIME is a standard that extends the format of email messages to support text in character sets other than ASCII, as well as attachments of audio, video, images, and application programs.
  1. Content-Type:
  • Specifies the type of content contained in the email, such as text, HTML, or attachments.
  1. X-Headers:
    • Additional custom headers that may be added by email servers or applications for specific purposes.

The email header is crucial for various reasons, including:

  • Routing Information: It shows the servers and paths the email took to reach its destination.
  • Authentication: Some headers provide information on email authentication methods used, helping to verify the legitimacy of the sender.
  • Spam Filtering: Email headers can contain information used by spam filters to assess the likelihood that an email is spam.
  • Troubleshooting: When dealing with email delivery issues, the header can be analyzed to identify potential problems in the routing process.

To view the email header in most email clients, you can look for an option like “View Source,” “Show Original,” or “View Message Source.” Analyzing email headers can be useful in understanding the journey of an email and in troubleshooting email-related problems.

Get a free 15 day trial of Pst Viewer Pro for Windows 11/10.