How to export Outlook email to .eml or .mbox format

What are .PST and .MBOX files?

Pst files and Mbox files both email messages.  While PST files proprietary to Microsoft Outlook, Mbox is an open specification used by email clients such as Mozilla Thunderbird.  RFC-822 and subsequently RFC-2822 are the open specifications documents that describe internet messaging and embody the structure of .eml files.   An MBOX file is a “mailbox” file which contains a collection of RFC-2822 email.  So .MSG is to .EML what .PST is to .MBOX.

RFC-822 was not directly adopted by Microsoft Outlook, the leading email client software in the world. Outlook email messages are stored in a single .PST file which may contain thousands of individual emails, messages including their file attachments. The specification for  creating a .pst file is proprietary, and is determined by Microsoft Corporation. The .pst specification was closed until Microsoft began publishing parts of the specification in 2010.
When Outlook exports a single email item from a .pst file, it is saved as a .msg file, which is also a proprietary Microsoft specification. Outlook .msg and .pst files requires Microsoft Outlook, or an Outlook viewer such as PST Viewer Pro.
Emails within a .mbox mailbox are concatenated and stored as in plain text. The start of a message within the .mbox file is delineated by a line with the word “From” followed by a space and the return pathe-mail address. 
Because RFC-822/2822 is an open specification it has been adopted by email client software such as Mozilla Thunderbird. It is still used to store and exchange email messages. Some companies prefer to store emails in this open standard, rather than in a proprietary standard.

Exporting Outlook to .EML/.MBOX

Microsoft Outlook does not directly support exporting email messages from a .pst or .msg files to .mbox or .eml files. To do this requires a third party add-in extension to Microsoft Outlook.
MessageExport is a useful add-in for Microsoft Outlook for exporting email messages to formats that missing from Outlook. MessageExport integrates tightly with Outlook’s main toolbar to allow users to select email messages from within Outlook and then export the emails directly to .eml or .mbox format.
Choosing the "Export to .eml" email export function.
Export to .EML from Outlook toolbar
In addition to .eml and .mbox, MessageExport also adds other export formats to Outlook, such as .pdf, .msg, mhtml, gif, tif, text, html, and many others.
Image shows dozens of email export operations that can be performed by MessageExport add-in for MS Outlook.
Export formats included with MessageExport
To export Outlook emails to PDF with MessageExport, click a message or messages in the Outlook message list so that they are highlighted. Next, select the export format from the MessageExport dropdown list (.eml or .mbox) and then click the Export button.  MessageExport may ask you to select a target folder, and once done will begin to export the selected emails.
If you export to .mbox, then all of your selected Outlook emails will be in a single .mbox file.
If you export to .eml, then you will have one .eml file for each Outlook email that was selected.
MessageExport also includes a “drag and drop” conversion capability.  Using MessageExport’s Export Folder Explorer, you can immediately convert a message to the selected format just by dragging that file and dropping on a folder in the explorer.
Drag and drop email conversion from MS Outlook.
Export folder explorer in closed state, resides on the right-hand side of the Outlook window. To use it, click to expand.

Selecting the appropriate folder for despositing email that has been converted.
Export folder explorer in expanded state.  Drag and drop email messages on the selected folder to immediately convert it to the currently selected format.
 MessageExport is a useful add-in for convert Outlook email message to .eml, .mbox, .pdf and other formats that are not natively included with Microsoft Outlook.  You can download a free 15 day trial of MessageExport.

A Simple .EML File Viewer

MessageViewer Lite is a simple .eml viewer with excellent email rendering abilities. MessageViewer Lite is capable of opening .eml files, Outlook .msg files and winmail.dat files.

Download a free trial of MessageViewer Lite .eml file viewer.

First, a bit of background.

Outlook Express (OE) is an email client that Microsoft distributed with its popular Microsoft Windows XP operating system. With XP still commanding about 40% of the desktop operating system market, Outlook Express remains an important email client for millions of people.
  

Saving individual emails from Outlook Express produces a file with the .EML extension. .EML files are an open email format specified in RFC-822 and RFC-2822.  In a single file, they can contain the email message (text and html formatting), the message header,  message path information, time/date information, file attachments, and other bits and bobs of information.

When someone wants to share an email message and its attachments from OE they may save it as a .eml file and then attach it to another email message.  Sometimes, .eml files are attached to a customer record in customer relationship software to remain part of the contact history. If an email client capable of opening .eml  files is not present on the computer when someone tries to open the .eml file, then the user may see an error message.  Being unable to open a .eml file at the moment its needed can be frustrating and unproductive.

A .eml file viewer can make it easy to open .eml files, even if Outlook Express or another capable email client is not installed on the computer.  EML file viewers can be very light, with a small software footprint, unlike a full email client package. 


A closer look at MessageViewer Lite

Installing and using the MessageViewer Lite .EML Viewer

MessageViewer Lite can be set as a the Windows system default software for handling .eml and .msg files, allowing the user to open email files simply by clicking on them.  MesageViewer Lite allows you to have multiple windows open at once, a nice convenience if you need to capture bits of information from several emails.
MessageViewer Lite was designed to be simple to use, and therefor has few advanced features. With MessageViewer Lite, you can copy the text of an email, print the message, or save it as a text file.  Files attached to the email can be saved to disk simply by dragging the file out of the email and dropping it to your desktop.
 MessageViewer Lite is available for installation from an .MSI file, which is good news for system administrators who want to do a silient installation. A 15 day trial  can be downloaded free of charge from the MessageViewer Lite website. This is an overview of the installation process. When you start MessageViewer Lite Setup, a welcome screen starts to begin guiding you through the installation process.
Notice that as you install MessageViewer Lite, there is no advertising or special offers, or attempts to install software on your computer other than MessageViewer Lite. This is an advantage of using a commercial .eml viewer like MessageViewer Lite; they have no financial incentive to install unwanted ads or tracking software on your computer. Their only goal is to provide you with a good experience so that you’ll pay a few dollars and buy the software.
MessageViewer Lite .eml viewer setup wizard.
MessageViewer Lite installation welcome screen

Click next to continue

MessageViewer Lite email viewer is ready to install.
Ready to install.

MessageViewer Lite will quickly assess your computer and if everything is ok, it offers to continue the installation. The next step would be the acceptance of the End-User License Agreement, a standard requirement these days. Click “I accept” and then “Continue” to start the process.

End user license agreement.
MessageViewer Lite EULA.

The Installation Process begins. A status bar shows you the progress as MessageViewer Lite installs.

Installation process: "Installing MessageViewer Lite" email viewer.
Installing MessageViewer Lite.

When the installation process concludes, MessageViewer Lite will open with a welcome message.

Email viewer welcome message on startup.
Welcome Message.

Let’s take a look at the options in the  File menu drop down list.
Open lets you select and open an email file.
Close will close out MessageViewer Lite.
Print will allow you to print the email message.
Check file associations will allow you to reset MessageViewer Lite as .msg, or .eml Windows default.

The MessageViewer Lite File Menu. Options are Open, Close, Print, Check file associations or Exit.
File Menu.

The “View” drop down list has only one option. It allows you to toggle between Text and HTML/Rich Text email viewing. If you want MessageViewer Lite to always open emails in Texxt mode, the select this option. Below is a before/after snippet showing MessageViewer Lite in HTML mode, and the next image shows it in Text mode.

Show .eml files in html or plain text. Select your preferences.
MessageViewer Lite in HTML/Rich Text viewing mode

Plain text viewing mode for .eml files.
MessageViewer Lite in Plain text viewing mode

Let’s look at MessageViewer Lite’s Help drop down menu next.

Help drop down menu for MessageViewer Lite.
Help Drop Down Menu.

About – This will provide the version number of your software. It’s always helpful to know this if you ever need to contact the support team for help viewing .eml files.

Buy Now! – If you haven’t purchased a license for MessageViewer Lite, selecting this option will take you directly to the product purchase page.

Registration – Enter your product activation code here after purchasing.

Start Logging – This is included as a support function. If you should even run into any difficult, you can create a Log File that you can share with the support team. The log file will help them understand the issue.

Check update now – See if there is a newer version of MessageViewer Lite available.

Configure Update – Tells MessageViewer Lite how often to check for software updates.

Registering MessageViewer Lite

To register MessageViewer Lite, first obtain a product activation code. Next, go to Help>Registration and enter the code, then click Activate.
Registration screen to activate MessageViewer Lite email viewer.
Software activation screen.

After MessageViewer Lite is activated, you will see an option here to “Release License.” This allows you to uninstall the software, and then move it to a different computer, a helpful feature that allows you to keep using MessageViewer Lite even if you upgrade to a different computer.

MessageViewer Lite EML Viewer

MessageViewer Lite is a very easy to use and capable email viewer for .EML and Outlook .MSG files. We hope you have found this overview of the product to be useful.  Download a free trial of MessageViewer Lite and try it out yourself!

If you are looking for a fully featured .eml viewer/extractor/converter with search capabilities, then look at PstViewer Pro.