An EML file is a single email message saved as its own document on your computer
An EML file is a plain-text record of one email — the message itself, all the headers (sender, recipient, date, subject), and any attachments encoded inside it. When you see a file ending in .eml on your computer, you are looking at an email that has been exported or saved outside of your email program's normal storage.
Most email programs — Outlook, Gmail, Apple Mail, Thunderbird — store messages in their own formats inside folders you cannot easily open with other programs. An EML file breaks that pattern. It is a universal format that almost any email program can read, which makes it useful when you need to move messages between programs or keep a backup copy that does not depend on one particular process staying installed.
You will most often encounter EML files when you export messages from your email program, when someone sends you an email as an attachment, or when your email program automatically saves a draft or sent message in a location you can browse with your file manager.
Key Takeaways
- An EML file contains one complete email message in a format that any email program can open, not just the one that created it.
- Email programs create EML files when you export messages, save drafts to a folder, or back up your email.
- You can open an EML file by dragging it into your email program, double-clicking it if your computer recognizes the format, or opening it with a text editor to read the raw content.
- EML files are smaller and more portable than the folder structures most email programs use, which makes them useful for sharing single messages or moving email between different applications.
Why your email program created EML files
When you export a message from Outlook, Gmail, Apple Mail, or Thunderbird, the program saves it as an EML file because that format is readable by nearly every email process. This is different from the program's native storage — Outlook uses .pst or .ost files, Gmail stores everything on Google's servers, and Thunderbird uses its own folder structure. An EML file is a bridge between these different systems.
You might also see EML files if your email program crashed or if you manually saved a message to your computer's desktop or Documents folder. Some programs also create temporary EML files when you are composing a draft, then delete them once you send. If you find an EML file sitting in a folder, it usually means either you (or someone else) exported that message intentionally, or the program saved it as a backup.
How to open an EML file
The simplest method is to double-click the EML file. If your computer recognizes the format, it will open in your default email program — usually the one you use most often. On Windows, this is often Outlook or Windows Mail. On a Mac, it is usually Apple Mail. The message will display exactly as it appeared in the original email program, with all formatting, sender information, and attachments intact.
If double-clicking does not work, you can drag the EML file directly into your email program's window. Open your email program, then drag the file from your file manager (File Explorer on Windows, Finder on Mac) into the program. Most email programs will import it and add it to a folder you choose.
If you want to read the raw content of the EML file — the actual text, headers, and encoded attachments — you can open it with any text editor. Right-click the file, select "Open with," and choose Notepad (Windows) or TextEdit (Mac). You will see the email's source code, which is useful if you are troubleshooting a problem or need to verify something about how the message was sent, but it is not the easiest way to read a normal email.
Moving emails between programs using EML files
EML files are the standard way to move individual emails from one program to another. If you are switching from Outlook to Gmail, or from Apple Mail to Thunderbird, you can export your messages as EML files from the old program, then import them into the new one. Most email programs have an "Export" or "Save As" option in the File menu that creates EML files.
The process is usually: open your email program, select the message or folder you want to move, choose File > Export (or the equivalent in your program), pick a location on your computer to save the files, and then open your new email program and import them. Some programs let you import an entire folder of EML files at once, which is faster than importing them one by one.
This method works well for a handful of messages or even a few hundred, but if you are moving your entire email history, exporting as EML files can be slow. In that case, your email program may offer a bulk export option that creates a single large file instead.
The difference between EML and other email file formats
EML is one of several formats used to store email. PST files (used by Outlook) and OST files (also Outlook, for server-based accounts) can hold thousands of messages in one file, along with your folder structure. MBOX files (used by Thunderbird, Apple Mail, and others) also bundle multiple messages together. EML files are different because each file contains exactly one message.
This makes EML files smaller and easier to share — you can email a single EML file to someone, or back it up to cloud storage without worrying about file size. But if you have thousands of emails to move, creating thousands of individual EML files is impractical. That is why most email programs offer both options: export as EML for individual messages, or export as PST or MBOX for bulk transfers.
When you might need to work with EML files
You will most likely encounter EML files in a few specific situations. If someone sends you an email as an attachment (which is unusual but happens), it will be an EML file. If you are backing up important messages before switching email programs, you might export them as EML files. If your email program crashes and you need to recover a message, you might find an EML file in a temporary folder on your computer.
EML files are also useful if you need to preserve an email for legal or record-keeping reasons. Because the format is universal and straightforward, an EML file is more likely to remain readable in ten years than a message stored inside a proprietary email program that may no longer exist.
Frequently Asked Questions
Can I open an EML file without an email program?
Yes. You can open an EML file with any text editor — Notepad, Word, or even a web browser — and read the message content. However, the formatting will be harder to read because you will see the raw email code, including headers and encoded attachments. For a normal reading experience, use an email program.
Is it safe to open an EML file from someone I do not know?
EML files are text-based and cannot execute code, so they cannot infect your computer with a virus just by opening them. However, if the EML file contains a malicious attachment (like an executable file), opening that attachment could be dangerous. Treat an EML file the same way you would treat any email from an unknown sender — open it, but do not read or run any attachments.
Why is my email program not opening EML files when I double-click them?
Your computer may not recognize EML as an email format, or it may be set to open EML files with a text editor by default. Right-click the EML file, select "Open with," and choose your email program from the list. If your email program does not appear, you can drag the EML file directly into the program's window instead.
Can I convert an EML file to PDF or another format?
Most email programs let you print an EML file to PDF, which preserves the message in a format that is straightforward to share and archive. Open the EML file in your email program, then use File > Print and select "Print to PDF" or "Save as PDF" depending on your operating system.
What happens to attachments when I save an email as an EML file?
Attachments are encoded and stored inside the EML file itself, not as separate files. When you open the EML file in an email program, you can read or save the attachments the same way you would from a normal email. If you open the EML file in a text editor, the attachments will appear as long strings of encoded text.