An MSG file stores a single email message with all its parts in one document

An MSG file is a single email saved as its own file on your computer. It contains the message text, subject line, sender and recipient addresses, attachments, and formatting — everything that was in that email when you saved it. MSG is the native format that Microsoft Outlook uses when you drag an email out of your inbox and drop it on your desktop, or when you right-click and choose "Save As".

The main reason you end up with MSG files is to keep a copy of an important email outside your email program. Once it's saved as an MSG file, you can move it to a folder, email it to someone else, or back it up separately from your email account. The file stays readable as long as you have software that can open it.

Key Takeaways

  • MSG files are individual emails saved as standalone files, created most often by Microsoft Outlook when you export or save a message.
  • You can open an MSG file with Outlook, Outlook on the Web, Windows Mail, or free third-party programs like Mozilla Thunderbird or eM Client.
  • If you receive an MSG file from someone else, you do not need Outlook installed — several free options will open it.
  • Converting an MSG file to PDF or another format is possible through Outlook or online conversion tools, though the original MSG file remains unchanged.

How MSG files are created

The most common way an MSG file appears is when you use Microsoft Outlook and save an email manually. You can do this by right-clicking any message in your inbox and selecting "Save As", then choosing a folder on your computer. Outlook creates the MSG file and stores it there. You can also drag an email directly from Outlook onto your desktop or into a folder, and Outlook will create an MSG file automatically.

MSG files also appear when someone forwards you an email as an attachment instead of forwarding the message itself. Rather than sending you the original email through your email account, they've saved it as an MSG file and attached it to a new message. This is less common but happens when people want to preserve an email exactly as it was, including all its original formatting and metadata.

Programs that can open MSG files

Microsoft Outlook is the most straightforward option — if you have Outlook installed, you can double-click an MSG file and it opens in Outlook as if it were still in your inbox. Outlook on the Web (the browser version of Outlook) can also open MSG files if you upload them through the interface.

If you don't have Outlook, several free programs will open MSG files. Mozilla Thunderbird is a free email client that reads MSG files natively. eM Client is another free email program that handles MSG files. Windows Mail, which comes built into Windows, can open MSG files as well. On a Mac, you have fewer native options — Apple Mail does not open MSG files directly, but you can use third-party programs like Mailbird or convert the file first.

Online conversion tools also exist: you can upload an MSG file to a website, and it will display the email content in your browser or convert it to another format. These tools vary in reliability and privacy practices, so research the site before uploading sensitive emails.

What information is stored inside an MSG file

An MSG file contains everything that was in the original email. This includes the sender's address, all recipient addresses (To, CC, and BCC), the subject line, the date and time it was sent, the message body with its original formatting, and any attachments. It also stores metadata like whether the message was marked as read, flagged, or assigned to a category in Outlook.

Because MSG files preserve all this information, they are useful for record-keeping. If you need to prove that an email was sent on a certain date, contained specific text, or included particular attachments, saving it as an MSG file creates a timestamped record that is harder to alter than a screenshot or a copy-paste.

Converting MSG files to other formats

If you need to share an email with someone who may not have software to open MSG files, you can convert it to a more universal format. The most common conversion is to PDF, which preserves the appearance of the email and can be opened on any computer. To convert an MSG file to PDF in Outlook, open the message and use File > Print, then select "Print to PDF" or a PDF printer.

You can also convert MSG files to other formats like EML (a more universal email format), HTML, or plain text. Online conversion tools can handle these conversions, or you can use Outlook itself — open the MSG file in Outlook, then export it in a different format through the File menu. The original MSG file is not affected by conversion; the new file is created separately.

Why you might receive an MSG file from someone else

When someone sends you an MSG file as an attachment, they usually have a specific reason. They may want you to see an email exactly as it appeared, with all original formatting intact. They might be forwarding an important message from a third party and want to preserve the original sender's information. Or they could be sharing a record of a transaction, agreement, or conversation that needs to stay in its original form.

Sometimes people send MSG files because they don't know how to forward an email normally, or because their email system doesn't support standard forwarding. In any case, opening the file is straightforward — use one of the programs listed above, and the email will display as a readable message.

Organizing and storing MSG files

Once you have MSG files on your computer, treat them like any other document. You can organize them into folders by date, project, or sender. Because they are individual files, you can search for them using Windows Search or Mac Spotlight by typing keywords from the subject line or sender name. You can also back them up to an external drive or cloud storage separately from your email account, which is useful if you want a permanent copy of important messages.

If you accumulate many MSG files, consider whether you actually need them all. MSG files take up disk space, and if the original emails are still in your email account, keeping both copies is redundant. Delete MSG files you no longer need, or move them to an archive folder if you want to keep them but don't access them regularly.

Frequently Asked Questions

Can I open an MSG file without Microsoft Outlook?

Yes. Mozilla Thunderbird, eM Client, Windows Mail, and several online conversion tools can all open MSG files without Outlook installed. If you receive an MSG file from someone, you have multiple free options for reading it.

Is an MSG file the same as an EML file?

No. EML is a more universal email format that works across many email programs, while MSG is specific to Microsoft Outlook and stores more metadata. Both contain a single email, but MSG files preserve more Outlook-specific information like categories and flags.

Can I edit an MSG file?

You can open an MSG file in Outlook and edit the message text, but the changes only affect your copy — they do not change the original email in anyone else's inbox. If you want to save the edited version, save it as a new MSG file.

What happens if I delete an MSG file?

The MSG file is deleted from your computer, but the original email remains in your email account unless you deleted it there too. MSG files are copies, so deleting the file does not affect your email inbox.

Can I convert an MSG file to PDF?

Yes. Open the MSG file in Outlook, go to File > Print, and select a PDF printer or "Print to PDF" option. This creates a PDF version of the email that anyone can view, though the PDF will not be interactive like the original MSG file.