What is MSG File Format: A Detailed Overview

Specification of .msg File Extension

Developer Microsoft
File Format .msg
File Type Encapsulated Message Item
Application Supported Microsoft Outlook
File Category Text Files
String Value DI.ait.a
File Hex Signature D0 CF 11 E0 A1 B1 1A E1
Format Type Text and Binary
Mime Type application/octet-stream

MSG File Format: Description, Location, and Structure


Microsoft Outlook uses MSG files as the email file format. MSG format is used for the storage of some essential things, which includes emails, contacts, messages, tasks, etc. It basically, stores the data as a single message with .msg extension. Moreover, elements like recipient, date, sender, content, attachments (images, screenshots, videos, etc.), etc., all these things together create a MSG format. To view MSG files with attachments MS Outlook is required.

The Outlook message file uses Compound File Binary format. This format works on a simplified file system which has a bunch of storage and stream elements. This storage and stream objects act as a directories and files. All message elements are contained in storage objects, whereas attributes by stream objects. Those applications that use MAPI (Messaging Applications Programming Interface) MSG files are compatible with them.

MS .msg file extension has various storage to store the message attributes. A MSG file contains following attributes:

  • Recipient
  • Embedded files
  • Attachments
  • Sender
  • Schedules/Appointments


MSG files created by drag and drop process. So, it does not have a particular file location.


If MSG file is accessed in Microsoft Outlook and Exchange Server then, the internal structure of MSG format is divided into three parts as mentioned below:

  • Email header: It contains header details or information, which includes sender, date, subject, and recipients, etc.
  • Email signature: The end of a selected message is identified by this signature.
  • Message body: It contains the main message parts like text, hyperlinks and other values.

Note: If you want to more understand internal details of MSG file then you can take the help hex editor, and you also able to export MSG files to PST with attachments by using our software.

Major Issues with MSG File Format

Users may face some challenges with this file. There is a possibility that MSG files can be corrupted due to some unwanted reasons. Following reasons are responsible for MSG file corruption:

Improper Shutdown

When the machine is not shutdown properly it can corrupt MSG file and make it difficult for the users to access the file. This improper shutdown can occur due to sudden power cut, some connection issues, etc.

Virus Attack

Nowadays, there are different kinds of harmful virus available in the online market. These viruses can spread from one system to another system very cleverly. MSG files can be corrupted by these viruses.

Hardware Issues

Apart from the above reasons, MSG files can be damaged by the hardware related issues. Any kind of damage in hardware can become one of the reasons for the corruption of Outlook MSG extension.

Some More Details of MSG files

There are various instructions that come while accessing the emails of MSG data files. Some of the instructions are mentioned below:

Enable to navigate Outlook message files

Users found the default location of MS Outlook data files in .pst file extension. Therefore, users who want to know the actual location of Outlook message file face some challenges. On the default location users will find either a PST file or OST file. To access all the mail messages of Outlook in MSG file format, need to follow the below instruction:

  1. Firstly, launch MS Outlook application on the device
  2. Now, restore down screen of Outlook and choose a message from Outlook at once.
  3. You need to drag-and-drop the selected email message to desktop in the next step.
  4. Finally users can find out the dragged mail message in .msg extension.

View Encrypt Algorithm on .msg File Extension

This file format helps to study the security algorithms embedded on MSG files. Now, follow these mentioned steps:

  1. First of all, click on Right option on MSG file and then, choose the option of Rename.
  2. Now, change extension to .txt and press enter key.
  3. Again, make a right-click on the items and select Calculate Hash Value tab.
  4. Once this is done, users will be able to see the encryption algorithms in list form that are imposed on the email message.


MSG file format is a very essential file developed by Microsoft. Therefore, in the above section we have discussed the entire description so that users can understand that what is .msg file extension. We have present with the specifications and various features.