How to Open MSG Files Without Outlook

Leena Taylor Paul
Updated: May 7, 2026 • Open • 8 Min Read

Summary: MSG is Microsoft’s compound binary format for individual Outlook messages. As a result, a plain text editor shows garbled bytes. Open an MSG file without Outlook using one of five practical options.

Use a free desktop MSG viewer like the EmailBakup Email Converter. It renders the message, headers, hex view, and attachments.
Open it in Mozilla Thunderbird after converting to EML.
Use a free browser-based MSG viewer or open MSG files in Gmail after converting them to EML (with the privacy caveat that you are uploading the message).
Convert MSG to EML, PDF, or HTML so any reader can open it.
Rely on the Windows File Explorer preview pane when a compatible preview handler is installed.

Why You Can’t Open MSG Files Without a Reader

The .msg extension is tied to Outlook. However, the underlying format uses a Microsoft Compound File Binary (CFB) container.

Specifically, inside that container, MAPI properties hold the message details (subject, from, to, body, headers). In addition, each attachment lives in a separate stream.

A program that does not understand MAPI sees only the raw bytes. As a result, opening an MSG in Notepad gives you a mix of unreadable characters and occasional readable fragments. Therefore, you need either an Outlook-aware viewer, a converter, or a tool that parses MAPI directly.

What’s Inside an MSG File?

Headers: From, To, CC, BCC, Subject, Date, Message-ID, and any X-headers from the original mail server.
Body: sits in plain text, RTF, and HTML where available, so a viewer can render whichever the original sender used.
Attachments: each file occupies a separate stream inside the container. The original filename and MIME type stay intact.
Properties: MAPI metadata such as read status, follow-up flag, importance, and conversation thread index.

Method 1: Use a Free Desktop MSG Viewer

A dedicated desktop viewer is the safest choice because the file stays on your machine. EmailBakup’s Email Converter opens MSG files in its free preview mode without requiring Outlook to be installed.

Steps to Open MSG with the Email Converter

First, download and install the Email Converter for Windows or macOS.
Next, click Open, then choose Email Data Files > MSG. Browse to your .msg file or a folder full of them.
The message appears in the left pane. Then the body renders in the main pane with full formatting. Tabs at the top let you switch between Properties, Message Header, and Hex View.
Finally, click any attachment in the message to save it to disk.

Tip: The same viewer also works for batches. Point it at a folder full of MSGs and you can browse them like an inbox without ever installing Outlook.

Method 2: Open MSG in Mozilla Thunderbird (via Conversion)

Thunderbird does not read MSG directly. However, it imports EML messages cleanly through the ImportExportTools NG add-on.

Steps to View MSG in Thunderbird

First, install Mozilla Thunderbird from thunderbird.net.
Next, add the ImportExportTools NG add-on. Restart Thunderbird.
Then use a free converter (such as Method 4 below) or any online MSG to EML tool (with the caveats in Method 3) to create an .eml copy of your message.
In Thunderbird, right-click Local Folders > ImportExportTools NG > Import messages > Import EML messages from a directory.
Finally, pick the folder containing your EML file. The messages appear in Local Folders with the body, headers, and attachments intact. The same EML output also lets you open the MSG file in Windows Live Mail if Thunderbird is not available.

Method 3: Free Online MSG Viewers (Use With Caution)

Also, browser-based MSG viewers exist and require no installation. Typically, you upload the .msg file and the page renders the message in your browser.

Privacy warning: An online viewer means you are uploading your message (and any attachments) to a third-party server. Therefore, avoid this method for anything sensitive, work-confidential, or under NDA. Stick to a local viewer instead.

Steps to Try an Online Viewer

First, search for “MSG viewer online” and pick a reputable service.
Next, drag your .msg file onto the upload area. The site parses the file and shows the body, headers, and attachments.
Finally, close the tab when you are done. Some services keep an upload history, so clear it if the option is available.

Method 4: Convert MSG to EML, PDF, or HTML

If you need to share, archive, or print the message, convert the MSG to a friendlier format:

EML: opens in Thunderbird, Apple Mail, Windows Mail, Outlook (if later installed), and any IMAP client that supports drag-and-drop import.
PDF: opens in any PDF reader and suits legal hold, sharing, and printing.
HTML: opens in any web browser. It also preserves formatting and inline images.

The Email Converter from Method 1 exports MSG to all of these. Simply drop your MSG(s) in, click Export, choose your target format, and pick a destination folder.

Method 5: Windows File Explorer Preview Pane

If a compatible MSG preview handler is installed, Windows can render the message inside the File Explorer preview pane. In short, this is the fastest option for a one-off check.

Steps to Use the Preview Pane

First, open File Explorer and press Alt + P to show the preview pane (or click View > Preview pane).
Next, click your .msg file. If a handler is registered, the body appears on the right.
If nothing appears, install a free MSG preview handler such as the one bundled with the EmailBakup viewer. Then restart File Explorer.

Related Reading:

Which Method Should You Choose?

Any sensitive or work-related MSG: use Method 1 (desktop viewer). The file stays on your machine.
Already on Thunderbird and willing to convert first: use Method 2.
Non-sensitive message and convenience matters most: use Method 3.
Need to email, print, or archive: use Method 4 (EML, PDF, or HTML).
Quick one-off read of a single file on Windows: use Method 5 if a preview handler is installed.

Common Errors and Fixes

MSG opens as garbled text in Notepad

This is the binary format showing through. Therefore, use a proper MSG viewer (Method 1), convert it first (Method 4), or rely on the preview handler (Method 5).

“No preview available” in File Explorer

No MSG preview handler is registered. As a result, install one and restart File Explorer. Alternatively, install Outlook or a free MSG viewer that ships with a preview handler.

Attachments inside MSG fail to save

Some MSG files carry read-only properties. Therefore, copy the .msg to a writable location first. Then open it with the viewer and save the attachment to a regular folder.

Online viewer rejects the file as invalid

The file may turn out to be a renamed binary or partly truncated. First, confirm the original .msg opens in another viewer. If only the online viewer fails, switch to Method 1 or Method 4 instead.

Frequently Asked Questions

What’s the difference between MSG and EML?

MSG is Microsoft’s proprietary binary format used by Outlook for single messages. In contrast, EML is the plain-text RFC-822 standard used by Thunderbird, Apple Mail, Windows Mail, and most other clients. As a result, converting MSG to EML preserves all headers, body content, and attachments, but makes the file readable in any modern mail client.

Will I lose attachments when converting MSG to PDF?

No, as long as the converter is configured to either embed attachments inside the PDF or save them in a sidecar folder. The EmailBakup Email Converter does both. Some basic print-to-PDF tools, however, render only the body and require you to download attachments separately.

Can I open multiple MSG files at once?

Yes. Point a desktop viewer like the Email Converter at a folder containing many MSGs. As a result, it loads them as a single browsable list. Similarly, Thunderbird does the same once they are converted to EML and imported.

Is it safe to open an MSG file from an unknown sender?

Open it in a reader that does not execute scripts or follow tracking pixels. In addition, desktop MSG viewers and Thunderbird with remote content blocked are both safe. However, avoid double-clicking attachments inside the MSG until you have confirmed the sender.

Does the free EmailBakup viewer have a file size limit?

No fixed cap. The viewer streams the MSG from disk, so large messages with multiple attachments still open. In short, performance depends mainly on disk speed and available RAM.