What MSG Files Are and How to Open Them

An MSG file is an email message saved as a single file on your computer

MSG stands for message, and it is the file format Microsoft Outlook uses to store individual emails. When you save an email from Outlook to your hard drive, desktop, or a folder, it becomes an MSG file. You can recognize one by the .msg extension at the end of the filename — for example, "Invoice_from_supplier.msg" or "Meeting_notes.msg".

The file contains everything that was in the original email: the subject line, the sender's address, the date it was sent, the message body, and any attachments that came with it. Unlike a screenshot or a PDF, an MSG file preserves the email in its original format, which means you can open it later and see it exactly as it appeared in Outlook.

MSG files are useful when you need to keep a record of an important email outside your email account, share an email with someone else as a file, or back up messages before deleting them from your inbox. They are also created automatically when you forward an email as an attachment instead of just copying the text.

Key Takeaways

MSG files are individual emails saved as files, created by Microsoft Outlook or exported from other email programs.
An MSG file contains the complete email — subject, sender, date, message body, and any attached files — in a single document.
You can open MSG files in Outlook, Outlook Express, Windows Mail, or free online viewers if you do not have Microsoft software installed.
MSG files are different from EML files, which are a simpler email format used by Gmail, Thunderbird, and other email programs.

How to open an MSG file on Windows

If you have Microsoft Outlook installed on your computer, opening an MSG file is straightforward. Double-click the MSG file, and it will open in Outlook automatically. The email will display in a new window showing the sender, subject, date, and full message body, just as it would in your inbox.

If you do not have Outlook, Windows Mail (built into Windows 10 and earlier versions) can also open MSG files. Right-click the MSG file, select "Open with," and choose Windows Mail from the list. If Windows Mail does not appear, click "Choose another app" and scroll down to find it.

For computers running Windows 11, the built-in Mail app may not open MSG files directly. In that case, you can use a free online MSG viewer — search for "MSG file viewer online" in your browser, upload the file to the website, and view the email without installing anything. These viewers work on any computer with internet access.

How to open an MSG file on Mac

Mac computers do not have a native program that opens MSG files the way Windows does. If you have Microsoft Outlook for Mac installed, you can double-click the MSG file and it will open in Outlook, just like on Windows.

If you do not have Outlook, your options are more limited. You can use a free online MSG viewer by uploading the file to a website in your browser. Alternatively, you can read a third-party process designed to read MSG files — search the Mac App Store for "MSG viewer" to see what is available.

Another option is to open the MSG file on a Windows computer or ask someone with Windows and Outlook to convert it to a PDF or another format you can open on your Mac.

The difference between MSG and EML files

Both MSG and EML files are email formats, but they work differently. EML files are a simpler, more universal format used by Gmail, Thunderbird, Apple Mail, and many other email programs. MSG files are specific to Microsoft Outlook and preserve more of Outlook's formatting and features.

If you export an email from Gmail, you get an EML file. If you save an email from Outlook, you get an MSG file. EML files are easier to open on different devices and programs — you can open one in almost any email client or even in a text editor. MSG files require Outlook or a specialized viewer.

In practice, this means if someone sends you an MSG file and you use Gmail or Apple Mail, you will need to use an online viewer or ask them to resend it as an EML file or PDF.

Why you might receive or create MSG files

You might receive an MSG file when someone forwards an email to you as an attachment instead of just forwarding the message itself. This happens when they want to preserve the original email exactly as it was, including all its formatting and any files attached to it.

You create MSG files when you save emails from Outlook to your computer for backup, archiving, or sharing. Some people save important emails as MSG files to keep them separate from their inbox, especially if they are cleaning up their email account or moving to a new computer.

Businesses sometimes use MSG files to store records of customer communications, invoices, or contracts. Because an MSG file contains the complete email with its date and sender information, it serves as a timestamped record that is harder to alter than a forwarded email or a screenshot.

Converting an MSG file to another format

If you need to share an MSG file with someone who cannot open it, or if you want to store it in a more universal format, you can convert it. The easiest way is to open the MSG file in Outlook, then use "File" and "Save As" to save it as a PDF. This creates a document anyone can read, though they will not be able to edit or forward it as an email.

You can also convert MSG to EML format if you have the right software. Some free online converters will do this — search for "convert MSG to EML" — though you should be cautious about uploading sensitive emails to unfamiliar websites. If the email contains personal or confidential information, converting it on your own computer using Outlook is safer.

Another option is to open the MSG file in Outlook and forward it as a regular email to yourself or someone else, which converts it back into a standard email format that any email program can read.

Frequently Asked Questions

Can I open an MSG file without Outlook?

Yes. You can use Windows Mail on a Windows computer, a free online MSG viewer in your web browser, or a third-party MSG reader process. Online viewers work on any device with internet access and do not require you to install software.

Is it safe to open an MSG file from someone I do not know?

MSG files themselves are not dangerous, but they can contain malicious attachments just like regular emails. If the MSG file came with an attachment you were not expecting, do not open the attachment. If you are unsure about the source, use an online viewer instead of opening it in Outlook.

Why can I not open my MSG file?

The most common reason is that you do not have compatible software installed. Windows Mail and Outlook are the main programs that open MSG files natively. If neither is available, use a free online MSG viewer. If the file is corrupted or incomplete, it may not open in any program.

Can I convert an MSG file to PDF?

Yes. Open the MSG file in Outlook, go to "File," select "Save As," and choose PDF as the format. This creates a document anyone can view, though the PDF will be a static image of the email rather than an editable or forwardable message.

What happens if I delete an MSG file?

It goes to your Recycle Bin (Windows) or Trash (Mac) and can be recovered if you empty it soon after. If you have already emptied the trash, the file is gone unless you have a backup copy stored elsewhere.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.