What an email file is and why you have one
An email file is a document your computer saved from an email message or your entire email account. The most common types are .eml files (single messages), .msg files (Outlook messages), and .pst or .ost files (entire mailboxes). You might have one because you exported messages from Gmail, Outlook, or another email program, or because someone sent you an archived email as an attachment.
Unlike a regular email sitting in your inbox, an email file is just data stored on your hard drive. Your computer needs the right program to read it, the same way it needs a photo viewer to open a picture file. If you try to open an email file with the wrong program, you'll see gibberish or an error message.
The steps to open it depend on what type of file you have and what email program (if any) is already on your computer. Most of the time, the solution is straightforward.
Key Takeaways
- Email files come in different formats (.eml, .msg, .pst), and the right program to open them depends on which type you have.
- If you use Outlook, Gmail, or Apple Mail, you likely already have a program that can open most email files without installing anything new.
- Double-clicking the file usually works if your computer recognizes the file type, but if it doesn't, you'll need to open the program first and then import the file.
- Web-based tools can open .eml and .msg files if you don't have the right program installed, though uploading sensitive emails to the internet carries privacy considerations.
The fastest way: double-click and let your computer decide
Start by finding the email file on your computer. Look in your Downloads folder, Desktop, or wherever you saved it. The filename will end with .eml, .msg, .pst, or .ost.
Double-click the file. If your computer recognizes the file type and has a program set to open it, the email will appear in that program. This works most often with .eml and .msg files if you have Outlook, Gmail, or Apple Mail installed. If nothing happens or you see an error, move to the next section.
Opening .eml files (single email messages)
.eml files are the most portable email format. They contain a single message and can be opened by almost any email program. If double-clicking didn't work, try these steps.
On Windows: Right-click the .eml file and select "Open with." A list of programs will appear. Look for Outlook, Windows Mail, Thunderbird, or Gmail. If you see one of these, click it. If you don't see any email programs listed, click "Choose another app" and scroll down — you may find more options. If you still see nothing, you'll need to install an email program or use a web-based tool (see the section below).
On Mac: Right-click (or Control-click) the .eml file and select "Open With." Look for Mail, Outlook, or Thunderbird. Click the program name. If the file opens but looks wrong, try a different program from the same menu.
Opening .msg files (Outlook messages)
.msg files are Outlook's native format. They usually open in Outlook, but can also open in other programs.
If you have Outlook installed, double-click the .msg file. It should open in Outlook automatically. If it doesn't, right-click the file, select "Open with," and choose Outlook from the list.
If you don't have Outlook, the file is harder to open. Thunderbird (a free email program) can open some .msg files, but not all. Windows Mail on newer Windows computers may also work. If none of these are on your computer, a web-based tool is your next option — see below.
Opening .pst and .ost files (entire mailboxes)
.pst and .ost files are large archives that hold hundreds or thousands of emails. These files are almost always associated with Outlook. If you have Outlook, you can import the file into your mailbox.
Open Outlook. Go to File menu and look for an option called "Open & Export" or "Import/Export" (the exact wording varies by version). Select "Import/Export." Choose "Import from another file or program" and then select "Outlook Data File (.pst)." Click Next, then browse to find your .pst or .ost file on your computer. Select it and click Open. Outlook will add the emails from that file to your mailbox, usually in a new folder.
If you don't have Outlook, opening these files is not straightforward. You would need to install Outlook, use a third-party tool designed for .pst files, or contact whoever created the file and ask them to export it as individual .eml files instead.
Using a web-based tool if you don't have the right program
If you have an .eml or .msg file and no email program on your computer can open it, you can use a free online tool. Search for "open eml file online" or "open msg file online." Several websites let you upload the file and view it in your browser.
Before you do this, understand the trade-off: you are sending your email file to someone else's server. If the email contains sensitive information — passwords, financial details, personal messages — this is a risk. Most of these tools claim to delete files after you view them, but you have no way to verify that. Use this method only for emails you don't mind a third party seeing, or only as a last resort.
If the file is important and contains sensitive data, installing Outlook or Thunderbird (both free) is safer than uploading to a web tool.
What to do if the file still won't open
If you've tried the steps above and the file still won't open, check these common problems.
The file is corrupted. Email files can become unreadable if they were damaged during download or transfer. Try downloading or copying the file again from wherever you got it. If it still won't open, the original file may be damaged beyond repair.
The filename is wrong. Sometimes a file is saved with the wrong extension. For example, an .eml file might be named "message.txt" by mistake. If you know what type of file it should be, try renaming it to the correct extension (for example, change "message.txt" to "message.eml") and try opening it again. Right-click the file, select "Rename," change the extension, and press Enter.
You need to install an email program. If your computer has no email program at all, download Thunderbird (free, works on Windows and Mac) or install Outlook if you have Microsoft 365. Both can open .eml and .msg files. After installation, try double-clicking the email file again.
Frequently Asked Questions
Can I open an email file without installing any programs?
Yes, if you use Gmail or Outlook online. You can drag and drop an .eml file into Gmail's compose window, and it will import the message. For Outlook online, the process is less direct, but you can forward the email to yourself if you can open it in any program first. Web-based tools also work but carry privacy risks.
What's the difference between .eml and .msg files?
.eml is a universal format that most email programs can read. .msg is Outlook's proprietary format and is harder to open in other programs. If someone sends you an email file and you're not sure which one to use, ask for .eml — it's more compatible.
I have a .pst file but no Outlook. Can I open it?
.pst files are designed for Outlook and are difficult to open without it. Your best option is to install Outlook (available free with Microsoft 365 or as a standalone purchase) or ask whoever created the file to export it as individual .eml files instead. Some third-party tools claim to convert .pst files, but they vary in reliability.
Is it safe to upload my email file to a web-based tool?
It depends on what's in the email. If it contains passwords, financial information, or anything private, uploading it to a stranger's server is risky. Most tools claim to delete files after viewing, but you cannot verify this. For sensitive emails, install a local program like Thunderbird or Outlook instead.
Why does my email file open but look like random characters?
The program you're using doesn't understand the file format. Try right-clicking the file, selecting "Open with," and choosing a different program. If you have Outlook, Thunderbird, or Apple Mail, try each one in turn. If none of them work, the file may be corrupted.