What is an MSO file?
An MSO file is a data container file format that is created when an HTML message is sent using Microsoft Outlook. This happens mostly with Microsoft Office 2000 applications. In most of the cases, the email message is attached with the name Oledata.mso file. The email recipient, when opens such an email, can view the file correctly even if they don’t have the same software installed. MSO files refer to Microsoft Compound Document File Format (MCDF).
Microsoft MSO File Format
MSO files are saved in Microsoft Compound Document File Format (MCDF) which is also known as the Object Linking and Embedding (OLE) or Component Object Model (COM) structured storage compound file implementation binary file format.
MSO File Format Structure
The internal file format structure of MSO file format is well-defined in the Structures section of MCDF documentation. The File Allocation Table (FAT) manages the sector allocation and sector chains. It contains an array of 32-bit sector numbers. Each index in the array represents a sector number whereas its value represents the next sector in the chain or a special value.