Files with mso extension can be found as special attachment for Microsoft Word documents send through e-mail to MS Outlook. Contains data to properly render the document as a HTML webpage in Outlook.

There are 3 other file types using
the MSO file extension!

mso icon.mso - Microsoft Organization Chart chart data

empty icon.mso - MedlySound module

empty icon.mso - ActiveMime object

Detailed description

Software that open mso file

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MSO file extension - OLE web page storage stream

What is mso file? How to open mso files?

File type specification:

Internet related file type icon Internet related file type

Email related data file type icon Email related data file type

mso file icon: mso filetype icon

File extension mso seems to have been in the past used for a special attachment format generated by earlier versions of Microsoft Word (and possibly other MS Office programs) in conjunction with earlier versions of Microsoft Outlook.

Typically this happens when Word is used as email editor, the document is being send out as the email body which is in HTML format. Usually found as oledata.mso file.

The mso file contains necessary information to properly render the attachment in the message in its originating program. This happens when the file is opened in Outlook 2000 and 2003, and was fixed in 2007 and later. However the "problem" is generated by the sender, not by the recipient.

If you have Outlook installed, you will not see this file, as the document will be rendered properly in HTML using the data from oledata.mso.

However if your computer does not have Outlook installed and you use other mail client, you will see the oledata.mso file as an attachment.

The mso file does not contain the actual document, which can be either found in the body of the e-mail message, or as another attachment as .doc file.

You can disable this function in Word by:

  • Open Microsoft Word
  • Go to Tools ► Options… ► General tab
  • Click the button E-mail Options…
  • You can set the HTML filtering options on the General tab
  • Confirm it by OK

This is not exclusive to Word, but just happened mostly with the word-processor. But same files were for example generated by FrontPage or when saving documents to office html format and possibly also with broken links to files like filelist.xml, editdata.mso and oledata.mso.

The default software associated to open mso file:

Microsoft Word icon

Microsoft Corporation logoMicrosoft Word  Microsoft Windows software

Company or developer:
Microsoft Corporation

A popular word processor that started with Word for MS-DOS in 1983 and for year is now a core application of Microsoft Office suite. Microsoft Word offers powerful word processing and text editor features that allow users to easy create high quality documents.

Almost every, if not every, computer user knows .doc and .docx Word documents.

Microsoft Outlook icon

Microsoft Corporation logoMicrosoft Outlook  Microsoft Windows software

Company or developer:
Microsoft Corporation

Microsoft Outlook is e-mail management tool and personal information manager distributed with Microsoft Office suite. Outlook integrates e-mail application, calendar, task manager, contact manager, note taking in to one application.

Microsoft Outlook is used as a stand-alone application and also can work with Microsoft Exchange Server and SharePoint Server.

The predecessor of Outlook was called Schedule+. The newest version is called Outlook 2016.

Help how to open:

This file cannot be opened directly. When you open the .doc file with a *.mso file together in older Outlook, the Word document will be rendered as HTML web page.

How to convert:

This file type is not meant for conversion, you can however convert the *.doc file to which the *.mso file is attached to.

List of software applications associated to the .mso file extension

Recommended software programs are sorted by OS platform (Windows, macOS, Linux, iOS, Android etc.)
and possible program actions that can be done with the file: like open mso file, edit mso file, convert mso file, view mso file, play mso file etc. (if exist software for corresponding action in's database).

Click on the tab below to simply browse between the application actions, to quickly get a list of recommended software, which is able to perform the specified software action, such as opening, editing or converting mso files.

Programs that can create mso file - OLE web page storage stream

Programs supporting the exension mso on the main platforms Windows, Mac, Linux or mobile. Click on the link to get more information about listed programs for create mso file action.

Microsoft Windows:

Main software associated with mso file by default:
Microsoft Word small icon Microsoft Word
Other suggested software:
Microsoft FrontPage small icon Microsoft FrontPage

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