What an MSG File Is and Why Your Email Creates Them

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

When you use Microsoft Outlook or some other email programs, you can save an email to your hard drive as an MSG file. The file contains everything that was in that email: the message text, the sender and recipient addresses, the subject line, the date it was sent, and any attachments. It is a way to keep a copy of an email outside your email program, the same way you might print a letter and file it in a folder.

MSG stands for "message" — it is straightforward the file format that Outlook uses to store individual emails. When you see a file ending in .msg on your computer, you are looking at a single email that someone saved. You might create one yourself by dragging an email out of Outlook onto your desktop, or you might receive one from someone else who sent you an email as a file attachment instead of forwarding it the normal way.

Key Takeaways

An MSG file is one complete email message saved as a single file on your computer, containing the text, addresses, subject, date, and any attachments.
Outlook creates MSG files when you save or export emails, but other email programs like Gmail or Apple Mail do not use this format by default.
You can open an MSG file by dragging it back into Outlook, double-clicking it if Outlook is installed, or using free online viewers if you do not have Outlook.
MSG files are useful for keeping permanent records of important emails or sharing a single email with someone without forwarding it through your email account.

When and why you end up with MSG files

You create an MSG file when you save an email from Outlook to your computer. The most common reason is to keep a permanent copy of something important — a contract, a job offer, a receipt, or proof that you sent or received something on a specific date. Once it is saved as an MSG file, the email stays exactly as it was, even if you later delete it from your inbox or your email account closes.

You might also receive an MSG file from someone else. Instead of forwarding an email through their email program, they saved it as a file and sent it to you as an attachment. This sometimes happens when people want to share an email chain with someone outside their organization, or when they are moving emails between different email accounts and want to preserve the original formatting and metadata.

How to open an MSG file

If you have Microsoft Outlook installed on your computer, the easiest way is to double-click the MSG file. Outlook will open it and display it as if it were a normal email in your inbox. You can read it, print it, or drag it back into a folder in Outlook to file it permanently.

If you do not have Outlook, you have other options. Gmail has a feature that lets you upload an MSG file and convert it to a Gmail message. Apple Mail does not open MSG files natively, but you can use free online MSG viewers — search for "MSG file viewer" and you will find several websites that let you upload the file and read it in your browser without installing anything. Some of these viewers also let you read the attachments separately.

If the MSG file contains attachments you need, you can also try opening it with a text editor or a file compression program, though the result will be harder to read. The most reliable method is still Outlook or a dedicated MSG viewer.

MSG files versus other email formats

Outlook uses MSG for individual emails, but there is also a format called PST (personal storage), which is a single file that holds an entire folder of emails, contacts, and calendar items. A PST file is like a backup of your whole Outlook account, while an MSG file is just one message.

Other email programs use different formats. Gmail stores emails in its own system and does not create files you can see. Apple Mail uses EML files, which are similar to MSG but simpler and work with more programs. If you need to move emails between different programs, EML files are often easier to work with because more software can read them.

If you have an MSG file and need to convert it to EML or another format, you can open it in Outlook and export it, or use a free conversion tool online. The content stays the same — only the wrapper changes.

Why MSG files matter for record-keeping

MSG files are useful because they are a snapshot. Once you save an email as an MSG file, it does not change if you delete the original from your inbox, if your email account is deleted, or if the sender deletes their copy. The file on your computer stays exactly as it was on the day you saved it. This makes MSG files valuable for keeping proof of important communications — job offers, rental agreements, purchase confirmations, or evidence in a dispute.

If you need to keep records of emails for legal or financial reasons, saving them as MSG files and storing them in a folder on your computer or on a backup drive is a reliable way to do it. You can also print MSG files to PDF if you want a format that is even harder to accidentally modify.

Frequently Asked Questions

Can I open an MSG file on my phone?

Not easily. MSG files are designed for computers. You can email the MSG file to yourself and open it on your phone as an attachment, but most phone email apps will not display it properly. Your best option is to open it on a computer first, then forward the email normally to your phone, or take a screenshot of the important parts.

What happens if I lose the MSG file?

The email is gone from that file, but if it is still in your email account, you can find it there and save it again. If you deleted it from your email account too, the MSG file was your only copy. This is why it is a good idea to keep MSG files of important emails in a folder you back up regularly.

Can I edit an MSG file?

Not directly. MSG files are meant to be read-only records. If you open one in Outlook and make changes, you are creating a new version, not editing the original file. If you need to edit the content, copy the text out of the MSG file into a new email or document instead.

Why would someone send me an email as an MSG file instead of just forwarding it?

Usually because they want to preserve the original email exactly as it was, including the original sender and date. When you forward an email, your email program adds a new layer showing that you forwarded it. Sending it as an MSG file keeps the original intact and makes it clear you are sharing someone else's message, not your own.

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.