3 steps to open file with MSO extension

Usually solving problems with MSO file is simple – just install proper software and open the file. Read the guide and open MSO file now!

MSO File Extension

  • File type Inline E-mail Attachment
  • File developer Microsoft
  • File category Misc Files
  • File popularity rating
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What is a(n) MSO file?

The file with the .MSO extension stores information that allows you to render a Microsoft Word 2000 attachment in an email as a web page. For proper operation it is necessary to have Microsoft Outlook 2000 or newer installed - otherwise the file will be displayed as a separate attachment.


How to open MSO file?

There could be multiple reasons for which the system does not support given file. In the case of MSO extension, it is probable that none of the installed programs support given file type. Therefore, user should undertake the following steps

Step 1: Install a program that supports MSO files

If an application that supports MSO files is installed on user’s system, but is not used to open such files by default, right-click on the file icon and choose "Open with" option from the menu. Next, select the proper application and check the "Always use the selected application to open this kind of files" box. The system will store this information in its registry and use the selected program to open files with MSO extension by default.

Hint for Mac OS users


For Mac OS users the procedure is analogous – open the file menu by right-clicking on the MSO file and choose "Information" option and select "Open with program" option. From the submenu select an application and click on "Change all" button.

Step 2: Find and download proper software

Inability to open MSO files may also be related to the lack of any application that supports given file being installed on the system. Should that be the case, user needs to download and install one of the following applications. Once installed, the system will automatically associate newly installed application with MSO files. If this step fails, see step 1.

Programs that support files with MSO extension

Step 3: Check the MSO file for errors

Sometimes, although relatively rarely, steps 1 and 2 might not lead to expected results. There can be several reasons for such situation to occur:

  • MSO file has been downloaded from the internet but for some reason it is incomplete. In such case the file should be re-downloaded and opened again.
  • Structure of given MSO file could be corrupted and as such the program is not able to open the file
  • Storage medium on which the file was stored is damaged
  • It is important to ascertain that the icon representing given file is not a shortcut a related MSO file no longer present in the location to which the shortcut points
  • If the user account has restricted access privileges it is advised to contact the system administrator or an IT expert

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