How to Export Outlook Email to .eml or .mbox Format

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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 path e-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.

EML Viewer Lite – A simple tool for opening .eml, .msg and .pst email files

Screen shot showing location of MailDex 'create project' button.

EML Viewer Lite is a fully capable email viewer offered at an affordable price. It’s a great multi-email format tool for open email content stored as .eml, .msg and even .pst files.

To use EML Viewer Lite (which is also marketed as Pst Viewer Lite), just locate the folder containing your email files using the folder structure navigation on the left-hand side of the screen. Click on the folder, and EML Viewer Lite goes to work listing all of your messages.

 

EML Viewer Lite email viewer
EML Viewer Lite main menu

You can browse individual emails from the list.  Double click on an email to open it in a full window view.

The toolbar provides quick access to EML Viewer Lite’s most useful features, including Reply, Reply All, Forward email, search, and print.

 

Reply/Forward to .eml files with EmlViewer Lite.
EmlViewer Lite toolbar includes reply/forward ability.

The Reply and Forward functions work with Microsoft Windows’ default email client, so its not necessary to enter any email account informatio into EML Viewer Lite.

EML Viewer Lite can search all of your .eml files based on many specific criteria.  For example you can search emails that fall within a date range. Search by sender address, or find a text string within the email files.

 

EML Viewer search screen. Search .eml files.
Search .eml files

Individual EML files can be saved to different formats. To do this, select the message you want to save.  Next go to Mail > Save Message As  and select the target format.

 

Convert .eml file to different formats
Save .eml files as pdf, other formats

How is EML Viewer Lite different from EML Viewer Pro?

All of the core functions are present, including EML to PDF conversion, search, reply, forward, reply all, print and more.

The major difference is in the quantity of emails. EML Viewer Lite can export eml files individually, while EML Viewer Pro can bulk export .eml files by the thousands.

If bulk conversion of .eml files is not your core need, then you will find EML Viewer Lite to be a very capable viewer able to provide quick access to your .eml, .msg and .pst email files.

Click here to download a free trial of EML Viewer Lite.