How to open a .msg file in Windows 10 and 11

Windows has no built-in .msg handler without Outlook. How to open one with Outlook, without Outlook, and how to fix the file association when the wrong program opens it.

On Windows the .msg format is native territory — but only if Outlook is installed. Without it, Windows has no idea what the file is, and even with it, the file association is easy to break.

If you have Outlook installed

Double-clicking should work. When it does not, the file association has usually been claimed by something else — often a text editor or an unrelated app installed later.

Right-click the .msg file.
Choose Open with → Choose another app.
Pick Outlook. If it is not listed, choose Look for another app on this PC and browse to OUTLOOK.EXE under Program Files.
Tick Always use this app to open .msg files.

On Windows 11 you can also set this under Settings → Apps → Default apps, then search for the .msg file type.

If you do not have Outlook

Windows itself ships no handler. The Mail app, Notepad, WordPad and Word all decline the format, and there is no free Microsoft download that adds support — Outlook is part of a paid Office or Microsoft 365 licence.

The practical answer is to open it in your browser. Go to the viewer, drag the file on, and the message renders with formatting, inline images and attachments. Nothing is installed and nothing is uploaded, which also means it works on a locked-down corporate machine where you cannot install software or run an installer without admin rights.

Why Outlook on the web does not help

A Microsoft 365 subscription alone is not enough: outlook.office.com cannot open .msg files. Emailing the file to yourself does not work either — it arrives as the same attachment the web client will not render. You need the desktop application specifically.

Opening a .msg without opening Outlook

Even with Outlook installed, there are reasons to avoid it: double-clicking a .msg launches the whole application, which is slow, and on a machine signed into someone else's mailbox you may not want to open it at all. Reading the file in a browser side-steps both.

Common Windows-specific problems

The file opens in Notepad as binary garbage. The association is pointing at a text editor. Fix it with the steps above — the file is fine.
Windows hides the extension. Turn on View → Show → File name extensions in File Explorer, so you can see whether a file is really a .msg.
The file came out of a ZIP and will not open. Extract it properly first; some programs open files "inside" a ZIP from a temporary location that gets cleaned up mid-read.
Blocked file warning. Files downloaded from the internet are marked. Right-click → Properties → tick Unblock.

If the file opens but looks wrong — blank body, missing images, mojibake — the troubleshooting guide covers each symptom.