Category: .eml

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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.
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Converting HTML Formatted .EML Email Files To .PNG, Other Image Formats

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How to Archive .EML Emails as PNG Image Files

Files with the .eml extension are RFC-822 formatted email messages. EML Viewer Pro is a tool for managing eml files, and converting them to different formats, including image files like PNG, GIF, TIF and BMP. 


Today’s tutorial will show you how to use EML Viewer Pro to convert a html email message into a PNG file.  Download and install the 15 day free trial of EML Viewer Pro so you can follow along.

Download Eml Viewer for email.




EML Viewer Pro can display your .eml and .msg email files in a list.  It’s easy to scroll through this list and browse your emails. You can also search your emails and display those that meet your specified criteria, such as a date range, from a certain sender, or emails that match a search query.

In our example, I have a html formatted .eml file that contains an advertisement from a computer sales company. Selecting the message from EML Viewer Pro’s message list causes the email to display.

Main menu view of EML Viewer Pro software
HTML formatted .eml file displayed in EML Viewer Pro


To export this message to PNG format, I simply select the PNG export file from the drop down list in the toolbar. It is possible to select many .eml files for conversion (type Ctrol-A to select all emails in the list).  To start the export operation from eml to png, I click the export button.

How to export eml file to PNG with EML Viewer Pro. Menu image.
Choose the PNG export profile and click the Export Button

The export button is the green down arrow that points to a yellow stack of paper (I drew a red arrow pointing to it in the above image).

The export operation will begin, and the email is formatted into a png file. The size of the png image file will vary with the length of the email.  In this example, you can see that the resulting PNG is quite long.  EML Viewer Pro has preserved the images and html formatting. The email header information is included in the top of the image.

Example of .EML email file that has been converted to a PNG image
EML file converted to PNG

Converting EML email files to PNG or other images are a good way to preserve emails for sharing or archiving. Because many html formatted emails have images that are hosted remotely, the contents of the email are not downloaded until the email is displayed. Saving the html email as a png file preserves a copy of the original message, and is not dependent upon the availability of a remote server.


EML Viewer Pro is a versatile tool that helps you transform your emails into many different formats. In addition to PNG, you can also format emails to pdf, csv (Excel), html, mhtml, and others. Download a free trial today and see what EML Viewer Pro can do for you.