How to open a .msg file without Outlook

Why .msg files will not open

A .msg file is not a text file with a different extension. It is a Compound File Binary Format container — the same OLE2 structure that older .doc and .xls files use. Inside it, the subject, sender, recipients, body, and every attachment are stored as separate internal streams, each keyed by a numeric MAPI property tag.

Because Microsoft never published it as an interchange standard, Apple Mail, Gmail, Thunderbird and mobile mail apps all decline to open it. On macOS, double- clicking a .msg file typically produces "There is no application set to open the document". On Android and iOS it usually downloads and then sits there, untouchable.

Method 1 — Open it in your browser (no software)

This is the fastest route and works identically on every operating system, including phones and locked-down work machines where you cannot install anything.

1. Go to the viewer on the home page.
2. Drag your .msg file onto the drop zone, or click to browse.
3. The message opens immediately, with formatting, inline images, recipients and attachments intact.

Because parsing runs entirely in your browser, the file never travels over the network. You can confirm this yourself: open your browser's developer tools, switch to the Network tab, and open a file — you will see no upload request. Or simply disconnect from the internet after the page has loaded and keep working.

Method 2 — Open it in Outlook

If you have Outlook for Windows or Mac installed, double-clicking usually works. If Windows opens the wrong program, right-click the file, choose Open with, pick Outlook, and tick Always use this app.

The web version of Outlook (outlook.office.com) cannot open .msg files. A common workaround — attaching the file to an email to yourself — does not help either, because the attachment stays a .msg that the web client will not render.

Method 3 — Convert to .eml and use your normal mail app

.eml is the standard RFC 822 format that every mail client understands. Converting gives you a file you can open natively, forward, archive or import.

1. Open the .msg file in the viewer.
2. Choose Export → Save as .eml.
3. Double-click the downloaded file. Apple Mail, Thunderbird and Windows Mail all open it directly.

See the full comparison of .msg and .eml for what is preserved and what is not.

Method 4 — Save it as a PDF

For sharing, filing or attaching to a legal or support ticket, PDF is usually the right destination. The step-by-step guide covers how to get a clean PDF that keeps the header block and expands link URLs.

Method 5 — Rename to .txt (diagnostic only)

Renaming the file to .txt and opening it in Notepad or TextEdit will show scattered readable fragments among binary noise. Attachments, formatting and non-Latin characters are unrecoverable this way. Treat it as a way to check that a file is not empty, not as a way to read a message.

Platform-specific notes

The methods above work everywhere. Windows, macOS, phones and Gmail each have enough of their own quirks to be worth their own section, and those follow below.

If the file opens but something looks wrong — a blank body, broken images, mojibake — the troubleshooting guide works through each symptom.

What about multiple files?

You can drop up to 50 files at once. They appear in a list you can filter and step through with J and K, which is considerably faster than opening an exported mail archive one file at a time.

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.

1. Right-click the .msg file.
2. Choose Open with → Choose another app.
3. Pick Outlook. If it is not listed, choose Look for another app on this PC and browse to OUTLOOK.EXE under Program Files.
4. 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.

Why macOS cannot open .msg files

A .msg file is not a document in any format macOS knows. It is a Compound File Binary container holding Outlook's internal MAPI properties — the same OLE2 structure as a legacy .doc, but with entirely different contents. The format breakdown covers what is inside one.

Because Microsoft never published it as an interchange format, Apple Mail, Mail.app plug-ins, Preview and Quick Look all decline it. Quick Look shows a generic file icon rather than a preview, which is often the first sign something is wrong.

Method 1 — Open it in your browser

This is the only method that needs nothing installed and works the same on an Intel Mac, an Apple Silicon Mac, and a locked-down work machine where you cannot install software.

1. Open the viewer.
2. Drag the .msg file onto the drop zone.
3. The message opens with its original formatting, inline images, recipients and attachments.

The file is parsed by JavaScript inside the page, so nothing is uploaded. You can confirm that in Safari's Web Inspector or Chrome's DevTools: open the Network tab, then open a file, and no request carries your data.

Method 2 — Convert to .eml and use Apple Mail

If you want the message to live in Apple Mail alongside everything else, convert it to the standard format first:

1. Open the .msg file in the viewer.
2. Choose Export → Save as .eml.
3. Double-click the downloaded file. Apple Mail opens it directly, and you can then drag it into any mailbox to keep it.

What .eml preserves and what it drops is worth reading if the message is evidence or an appointment rather than ordinary mail.

Method 3 — Outlook for Mac

Outlook for Mac has never handled .msg files as smoothly as the Windows version. Double-clicking frequently does nothing at all. What usually works instead is dragging the file directly into a mail folder in the Outlook window, which imports it as a message you can then open normally.

Note that Outlook on the web cannot open .msg files at all, so a Microsoft 365 subscription on its own does not solve this. Emailing the file to yourself does not help either — it arrives as the same unreadable attachment.

Method 4 — Save it as a PDF for filing

If the goal is to archive the message or attach it to a ticket, PDF is usually the real destination. The PDF guide covers how to get a clean, paginated document with the header block intact.

What does not work

• Renaming to .txt and opening in TextEdit. You will see scattered readable fragments among binary noise. Attachments, formatting and any non-Latin characters are lost. Use it only to confirm a file is not empty.
• Quick Look and Preview. Neither has a handler for the format.
• Changing the extension to .eml. The two formats are structurally unrelated; renaming does not convert anything, and Apple Mail will either refuse the file or show gibberish.

Opening many files at once

Select them all and drag them in together — up to 50 at a time. They appear in a list you can filter, and J and K step between them. That is considerably faster than converting an exported archive one file at a time.

Why phones cannot open .msg files

.msg is Outlook's proprietary desktop format — a binary container of MAPI properties rather than a standard email file. iOS and Android both handle .eml natively but have no idea what to do with .msg. Even Microsoft's own Outlook mobile app declines it.

On iPhone and iPad

1. Tap the attachment in Mail, Messages or wherever you received it.
2. Tap the Share icon, then Save to Files. Choose somewhere you will find again, such as On My iPhone → Downloads.
3. Open the viewer in Safari.
4. Tap the drop zone, choose Browse, and pick the saved file.

The message opens in the browser. Attachments download to the Files app, where you can open them with whatever app normally handles that type.

On Android

1. Tap Download on the attachment.
2. Open the viewer in Chrome.
3. Tap the drop zone, then pick the file from Downloads.

Some Android mail apps hand the file straight to a "choose an app" dialog with nothing suitable listed. Save it first rather than trying to open it from that dialog.

Your file stays on your phone

Parsing runs inside the browser tab, so the message is never uploaded. This matters more on mobile than on a desktop: a phone is often where you read work mail on a personal device, and the alternative tools all require sending the file to a server you know nothing about.

Because there is no upload, it also works on a slow or metered connection — only the page itself is downloaded, once.

Getting the attachments

Every attachment inside the message can be downloaded individually, or all at once as a ZIP. On iPhone they land in Files; on Android in Downloads. Inline images — logos and signature graphics — are shown in the message body rather than listed separately, so the attachment list stays limited to what was really attached.

What does not work on a phone

• The Outlook mobile app. It will not open a .msg attachment, even with a Microsoft 365 subscription.
• Renaming the file. Mobile file managers often hide extensions, and renaming would not help anyway — the formats are structurally unrelated.
• Most "file viewer" apps from the store. Those that do claim .msg support usually upload your file to their own server to convert it.

If you need it on a computer later

Open the file on your phone and use Export → Save as .eml. The resulting file opens natively in Apple Mail, Outlook, Thunderbird and Gmail, so you can forward it to yourself and have something readable at the other end. See the format comparison for what changes in the conversion.

Why Gmail cannot preview .msg files

Gmail previews formats it understands — PDF, Office documents, images — using Google's own converters. .msg is Outlook's proprietary binary container, not a document format, and Google has never implemented support for it. You get "No preview available" and a download button.

Uploading the file to Google Drive does not help either, for the same reason: Drive stores it happily but cannot render it.

The quickest route

1. Download the attachment from Gmail.
2. Open the viewer in another tab.
3. Drag the file onto it.

The message opens with its formatting, inline images and attachments intact. The file is parsed inside the browser, so it is not uploaded to us — which is worth noting when the message arrived at a work address.

If you need it back inside Gmail

Gmail does display .eml attachments, so converting solves the problem properly:

1. Open the .msg file in the viewer.
2. Choose Export → Save as .eml.
3. Attach the .eml to a Gmail message instead.

Recipients can then open it directly. The conversion guide covers what is preserved and what is lost.

Forwarding a .msg to someone else

If you forward the .msg as-is, whoever receives it hits exactly the same wall unless they have Outlook. Converting to .eml first is the courteous option — it opens natively for essentially everyone, including the person reading it on a phone.

What Gmail does to the file on the way

Worth knowing before you blame the viewer: Gmail does not modify a .msg attachment, but its interface can make it look as though something did.

• The preview pane cannot open it, so Gmail falls back to a generic file icon. That is not a sign the file is damaged — Gmail has no .msg renderer at all.
• Downloading several attachments at once gives you a ZIP. The .msg inside it is intact, but you have to extract it first; opening it from inside the archive viewer often fails.
• Gmail may rename it. Duplicate names gain a (1) suffix, and some subjects produce names your operating system then truncates. The contents are unaffected — the format is identified by its bytes, not its name.

Messages that arrive as an attachment inside an attachment

A forwarded Outlook message frequently contains other messages nested inside it. Gmail shows only the outer file, so a thread that was forwarded as a bundle looks like a single attachment.

Opening it in a viewer that understands embedded messages reveals the rest. This matters most when the message you actually need is the innermost one — a forwarded approval, or the original of a complaint — which Gmail will never surface on its own.

Why the file arrived as .msg in the first place

Usually because the sender dragged a message out of Outlook onto their desktop, or used File → Save As, which produces .msg by default. Outlook's own Forward as attachment also attaches messages in this format. None of that is deliberate — most senders do not realise the file is unreadable outside Outlook.