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.MSO File Extension

A .MSO file is a Outlook In-Line Office Attachment, created by Microsoft.

Open with Should not be opened manually. Available for Windows and Mac.

What is a .MSO file?

An .MSO file is a special type of file that is created when you save a Microsoft Office document, like a Word or Excel file, as a webpage. This file is used to store information about any macros or OLE (Object Linking and Embedding) objects that were in the original document. Macros are scripts that can automate tasks within the document, and OLE objects can be things like charts or tables that are linked or embedded from other files.

When a Microsoft Office document is saved as a webpage, the .MSO file acts somewhat like a style sheet, which means it helps define the appearance and function of the webpage version of the document. However, the contents of an .MSO file are encoded, which means they are in a format that is not easily readable by humans. You might be able to open an .MSO file with a text editor (like Notepad), but it will look like a jumble of characters and won't make much sense.

It's important to note that you generally should not try to open .MSO files manually. These files are typically sent as email attachments when Office documents are shared via email after being saved as webpages. Opening .MSO files directly can be risky because they can sometimes contain viruses or harmful scripts. If you see an .MSO file attached to an email, it's best not to open it, especially if you weren't expecting it or if it comes from an unknown source. The safest approach is to avoid opening .MSO files unless you are sure they are safe and are from a trusted sender.

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