Email files are usually stored as .eml, .msg, or .mbox files, and you can open them with your regular email program or a free file viewer

An email file is a single message or a collection of messages saved to your computer as a document, the same way you might save a Word file or a PDF. The three most common formats are .eml (used by Outlook, Thunderbird, and Apple Mail), .msg (Microsoft Outlook's native format), and .mbox (a format that holds many emails in one file, used by Gmail, Thunderbird, and others). Which one you have depends on which email program created it or exported it.

The simplest way to open an email file is to double-click it. If your computer recognizes the format, it will open in whatever email program you have installed. If nothing happens, or if you get an error, you have other options: you can open it with a different program, import it into your email account, or use a free online viewer. The right choice depends on whether you want to read the email once or keep it organized with your other messages.

Key Takeaways

  • .eml files open in most email programs by double-clicking, but .msg files often need Outlook or a dedicated viewer.
  • If double-clicking does not work, you can right-click the file, choose "Open with", and select an email program from the list.
  • Importing an email file into your email account lets you search it and organize it alongside your other messages.
  • Free online viewers like Encryptomatic MailReader or EmlViewer let you read email files without installing anything new.

Opening an email file by double-clicking

Start by locating the email file on your computer. It will have a name followed by .eml, .msg, or .mbox. Double-click it. If your computer recognizes the format and you have an email program installed, the file will open in that program and you will see the message or messages inside.

If double-clicking opens the file in a text editor (showing code instead of a readable email), your computer does not know which program should open it. Close the text editor and try the next method instead.

Opening an email file with "Open with"

Right-click the email file. A menu will appear. Look for an option that says "Open with" or "Open with..." and click it. You will see a list of programs on your computer.

For .eml files, look for Outlook, Thunderbird, Apple Mail, or Gmail. For .msg files, Outlook is the best choice, but you can also try Thunderbird. For .mbox files, Thunderbird handles them well. Click the program name and the file will open in that program. If the program you want is not in the list, click "Browse" or "Choose another app" to find it manually.

Importing an email file into your email account

If you want to keep the email organized with your other messages instead of just reading it once, you can import it into your email account. The steps vary by program.

In Outlook: Click File, then Import, then select the file format. Follow the prompts to choose the file and the folder where you want it to go.

In Thunderbird: Click Tools, then Import, then select the file type. Choose the file and Thunderbird will add it to your inbox or a folder you specify.

In Gmail: You cannot import directly, but you can forward the email to yourself or use a third-party tool like CloudHQ or Thunderbird to sync the messages into Gmail.

In Apple Mail: Click File, then Import Mailboxes, then select the file. Choose where you want the messages to appear in your mailbox.

Using a free online viewer

If you do not want to install a new program or import the file into your email account, you can use a free online viewer. These websites let you upload an email file and read it in your web browser without saving anything to your computer.

Encryptomatic MailReader (mailreader.com) works with .eml, .msg, and .mbox files. Upload your file, and it will display the message, attachments, and headers. EmlViewer (emlviewer.com) handles .eml files. Neither of these services stores your file after you close the page, but read their privacy policies if you are concerned about uploading sensitive emails.

Extracting attachments from an email file

Email files often contain attachments — documents, images, or other files that were sent with the message. When you open an email file in an email program, you can usually right-click the attachment and save it to your computer, or double-click it to open it directly.

If you are using an online viewer, look for an "Attachments" section or a read button. Some viewers let you read attachments one at a time; others let you read them all at once as a .zip file. If the viewer does not show attachments, try opening the file in Thunderbird or Outlook instead, which will always display them.

Troubleshooting when an email file will not open

If you have tried double-clicking and "Open with" and nothing works, the file may be corrupted or in a format your computer does not recognize. Try these steps: First, make sure the file extension is correct. Right-click the file, click Properties (or Get Info on a Mac), and check that the name ends in .eml, .msg, or .mbox. If it ends in something else, the file may have been saved with the wrong extension.

Second, try opening it with a different program. Thunderbird opens .eml, .msg, and .mbox files, so if you have it installed, it is worth trying. Third, use an online viewer as a backup. If an online viewer can read the file, your email program may have a compatibility issue, and you can save the message content by copying and pasting it into a new email or document.

If none of these work, the file may be damaged. Ask whoever sent you the file to resend it, or ask them to export it again from their email program.

Frequently Asked Questions

Can I open an .msg file without Outlook?

Yes. Thunderbird opens .msg files, and so do free online viewers like Encryptomatic MailReader. You can also right-click the file and choose "Open with" to see what other programs are available on your computer.

What is the difference between .eml and .msg?

.eml is a plain-text format that most email programs understand. .msg is Microsoft's format and works best in Outlook, though other programs can read it. If you have a choice, .eml is more portable because more programs support it.

Can I convert an email file to PDF?

Yes. Open the email file in your email program or an online viewer, then look for a Print or Export option. Choose "Print to PDF" or "Save as PDF" and the email will be saved as a PDF file you can read or share.

Is it safe to upload my email file to an online viewer?

Most reputable online viewers delete your file when ready after you close the page. Read the privacy policy before uploading if the email contains sensitive information like passwords or financial details. If you are uncomfortable uploading, use Thunderbird or another desktop program instead.

What if the email file is very large?

.mbox files can contain thousands of emails and be hundreds of megabytes in size. Online viewers may not handle very large files. Try importing it into Thunderbird or Outlook instead, which can handle large files better. If your email program is slow, import the file into a new folder rather than your main inbox.