An MSG file is an email message saved by Microsoft Outlook

An MSG file is a single email message stored as its own file on your computer. Outlook, Microsoft's email program, creates MSG files when you save an email to your hard drive, forward it as an attachment, or export messages from your inbox. The file contains everything that was in that email: the subject line, the message body, any attachments, and metadata like who sent it and when.

You will most often encounter MSG files when someone sends you an email as a file attachment, or when you have exported old emails from Outlook for backup or archiving. Unlike a regular email sitting in your inbox, an MSG file is a standalone document that exists independently of any email program.

MSG files are specific to Microsoft products. If you use Gmail, Yahoo Mail, or another non-Outlook email service, you will not create MSG files unless you deliberately export messages into that format. The file extension is always .msg — you will see it at the end of the filename, like "Invoice_2024.msg".

Key Takeaways

  • MSG files are individual emails saved as files, created by Microsoft Outlook or exported from Outlook into a standalone format.
  • You can open an MSG file in Outlook, Outlook on the Web, or free third-party programs like Windows Mail or Mozilla Thunderbird.
  • If you do not have Outlook installed, you can still read MSG files by converting them to PDF or using an online viewer.
  • MSG files preserve the original email formatting, attachments, and metadata, so the message looks exactly as it did when sent.

How to open an MSG file in Outlook

If you have Microsoft Outlook installed on your computer, opening an MSG file is straightforward. Double-click the MSG file, and Outlook will open it in a new window. The email will display exactly as it appeared in your inbox, with all attachments visible and ready to download.

If double-clicking does not work, right-click the MSG file and select "Open with". A menu will appear showing programs on your computer. Choose Microsoft Outlook from the list. If Outlook does not appear, click "More apps" or "Choose another app" to find it.

Once the email is open in Outlook, you can read it, download any attachments, forward it, or print it. You can also drag the MSG file directly into an Outlook folder to import it into your inbox permanently.

Opening MSG files without Outlook installed

You do not need Outlook to read an MSG file. Several free programs can open MSG files on Windows and Mac computers. Windows Mail (built into Windows 10 and 11) can open MSG files directly. Mozilla Thunderbird, a free email program, also opens MSG files and works on Windows, Mac, and Linux.

On a Mac, you can use Apple Mail to open MSG files, though the process requires a few extra steps. You may need to drag the MSG file into Apple Mail or use the File menu to import it. Alternatively, Thunderbird works the same way on Mac as it does on Windows.

If you want to avoid installing new software, you can convert the MSG file to a different format. Many online conversion tools will turn an MSG file into a PDF, which you can then open in any PDF reader. Search for "MSG to PDF converter" in your web browser, upload the file, and download the converted version.

What information is stored in an MSG file

An MSG file contains far more than just the visible email text. It stores the sender's email address, the recipient list, the subject line, the date and time the email was sent, and the full message body with all original formatting — bold text, colors, fonts, and line breaks all remain intact.

Any attachments included in the original email are embedded in the MSG file itself. When you open the MSG file, you will see those attachments listed and can download them. The file also preserves metadata like whether the email was marked as read or unread, flagged, or assigned to a category in Outlook.

This completeness is why MSG files are useful for archiving. If you need to keep a record of an important email with all its details and attachments, saving it as an MSG file ensures nothing is lost.

MSG files versus other email formats

MSG files are not the only way to save emails. EML files are similar but use a different format that more email programs recognize. PST files are Outlook's format for storing entire mailboxes — many emails together in one file, rather than one email per file. MBOX files are used by Gmail, Thunderbird, and other email programs to archive messages.

If you receive an MSG file but want to convert it to a more universal format, you can open it in Outlook and export it as an EML file instead. EML files open in more email programs and are easier to share across different platforms. The process is the same as converting to PDF: use an online converter or open the MSG file in Outlook and use the export function.

Why you might receive an MSG file

Someone sends you an MSG file when they want you to have a copy of an email exactly as it was, complete with attachments and formatting. This is common in business settings when forwarding important correspondence, contracts, or records. It is also used when archiving emails for legal or compliance reasons, since the MSG format preserves all the original details.

You might also create MSG files yourself if you use Outlook and want to back up important emails, share them with someone who does not have email access, or keep a record of a transaction or agreement. Saving an email as an MSG file is a way to turn it into a permanent document that will not disappear if you delete it from your inbox.

Frequently Asked Questions

Can I open an MSG file on my phone?

Most phone email apps do not open MSG files directly. Your best option is to convert the MSG file to PDF on a computer first, then transfer the PDF to your phone. Alternatively, forward the MSG file to your email address and open it as a regular email in your phone's mail app.

What if an MSG file will not open?

The file may be corrupted or incomplete. Try opening it with a different program — if Outlook does not work, try Thunderbird or an online converter. If none of those work, the file itself may be damaged and cannot be recovered.

Can I edit an MSG file?

You cannot edit the original email content inside an MSG file. You can open it, read it, and download attachments, but to make changes you would need to convert it to a different format or recreate the email in your email program.

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

MSG files themselves are safe — they are just email data. However, any attachments inside the MSG file carry the same risks as any file from an unknown source. Do not download attachments from MSG files sent by people you do not trust.

How do I convert multiple MSG files at once?

If you have many MSG files to convert, use a batch converter tool online or in Outlook. Search for "batch MSG converter" to find tools that process multiple files together. Alternatively, open Outlook and import all the MSG files into a folder, then export the entire folder as a PST or EML file.