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.

Converting .EML Messages to PDF

It’s nearly impossible to do business these days without Adobe’s PDF viewer. The  PDF “Portable Document Format” has founds its way into nearly every computing device. Many corporations and libraries are archiving .eml email messages as .pdf files because it’s seen as a safe format that will be supported well into the foreseeable future and beyond, ensuring that emails will be.  There are very few software tools available today that can reliably batch convert .eml files to .pdf, and do so in a way that manages file attachments correctly.

EML Viewer Pro can read in your .eml and .msg files immediately, without the need for lengthy indexing. Just select the emails you want to export, click the export button and choose your mode of PDF export.  PST Viewer Pro also supports the PDF/A format which is perfect for long term .eml email file archiving.

Email manager. Select PDF format for .eml export.
Export Manager is where you choose your target eMail format.

When planning your eml-to-pdf export operation, ask yourself how you would like to deal with file attachments.  The tool you select should give you the flexibility to manage attachments in at least three ways:

  1. Extract file attachments. This capability will allow you to export your email to a PDF image, but will store any file attachments outside of the PDF in folder.
  2. Convert file attachments into the PDF image. This works well for document files like Word .DOC or Excel .xls files, but not so good for proprietary document formats and binary files.
  3. Embed file attachments. This option will take file attachments and store them as a separate file within the PDF. They can later be extracted to disk. This option has the advantage of keeping the file and the message together, preserving the context.

While exporting email to PDF, you’ll also want to have the capability to apply a specific name structure to your files.  EML Viewer provides this capability, allowing you to mix and match different parts of the email content into the PDF file name, including the title, date, sender or receiver. You can also apply a sequential number to the file.  Naming your exported .eml files in a logical manner will help you sort and identify the messages you need, right from the Windows files system.

While converting .eml files into .pdf files, use the file naming criteria to give your .pdf files a unique name.
.Eml file naming.

Long into the future, PDF format is bound to be supported because it is an open format, and because of its ubiquity. So future proof your .eml files by converting them to PDF with PST Viewer Pro.

Click here to purchase EML Viewer Pro.

See related article: Bulk conversion of EML to PDF