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.MSG·File Extension

MSG Document — A .msg file is a MSG Document. It is a document format used for word processing, spreadsheets, presentations or ebooks.

Documentapplication/vnd.ms-outlook

Quick facts

Extension.msg

File typeMSG Document

MIME typeapplication/vnd.ms-outlook

CategoryDocument

Charset—

CompressibleNo

What is .msg

What is a .msg file?

A .msg file is a MSG Document. It is a document format used for word processing, spreadsheets, presentations or ebooks.

In the mime-db registry it maps to application/vnd.ms-outlook, and it is marked as non-compressible. When serving .msg over HTTP, set the Content-Type header as shown in Developer info below.

Related entities: it maps to application/vnd.ms-outlook and is used by OMNeT++ MSG, ROS Interface among others — and is delivered over HTTP via the Content-Type header.

How to open .msg files

Use Microsoft 365 or LibreOffice to open and edit .msg files.
Any text editor (Notepad, VS Code) can inspect the raw content as text.

Developer info

When served over HTTP, responses should set the following header:

Content-Type: application/vnd.ms-outlook

Common software that reads/writes .msg:

Microsoft 365LibreOfficeAdobe AcrobatGoogle Docs

Relation chain

.msgextension of

format

MSG Documentserved as

mime type

application/vnd.ms-outlooksent via header

http header

Related extensions

Related MIME types

application/vnd.ms-outlook

.msg

Related programming languages

Common uses

Reports and letters
Spreadsheets and budgets
Presentations
Ebooks

How to edit .msg files

Open the file with Microsoft 365, make your changes and save.
Most editors preserve the original formatting and encoding — avoid changing the charset.

How to create .msg files

Create a new file and save it with the .msg extension, or export this format from Microsoft 365.

Frequently asked questions

What programs can open .msg files?

Common options include Microsoft 365, LibreOffice, Adobe Acrobat. You can also open many of these files with built-in viewers or a browser.

How do I create a .msg file?

Create a new file in any text editor or the app that owns the format and save it with the .msg extension.

What is the relationship between .msg and the application/vnd.ms-outlook MIME type?

application/vnd.ms-outlook is the media type identifier used for .msg files during network transfer (for example in the HTTP Content-Type header).

Sources & standards

Updated 2026-08-18

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