EML viewer
Open an .eml file without installing Outlook or Thunderbird. Drop a saved message below, or load the sample to see how it works, and this tool reads it in your browser: the From, To, Subject, and Date, the HTML and plain-text versions of the body, and any attachments. The file is parsed on your own machine and never uploaded.
What is an .eml file?
An .eml file is a single email message saved to disk. It holds the raw message exactly as it traveled: the headers, the body, and any attachments, all in one plain-text file that follows the RFC 5322 and MIME formats. Most mail clients can export a message as .eml, so you often end up with one when you save or forward a message for a receipt, a bug report, or a legal record.
Because the format is a documented standard, any .eml file can be read by any client that understands it. You do not need the program that created it. That is why a saved message from Outlook opens fine in Apple Mail, and why a viewer like this one can read it without either app.
How to open an .eml file
On a Mac, double-clicking usually opens the file in Apple Mail. To read it without importing it into your mailbox, drag the file onto the tool above, or right-click the file, choose Open With, and pick a text editor to see the raw source.
On Windows, a double-click typically opens the file in Outlook or the Mail app. If you do not have a mail client installed, or you do not want the message added to an account, open it in Notepad for the raw text, or drop it into the viewer above.
In the browser, use the tool on this page. Choose the file or drag it in, and it renders the message without any app. This is the fastest option when you are on a machine that has no mail client, or when you only want to inspect a message rather than file it.
What is inside an .eml file
Three things, stacked in the same file.
Headers come first. They record who sent the message, who it was addressed to, the subject, the date, and the path it took. Alongside the familiar From and To lines sit the technical headers that mailbox providers actually read: Received lines that trace each hop, and DKIM-Signature and Authentication-Results that show whether the message passed authentication. If you are trying to work out why an email went to spam, these are where you look first.
The body comes next, and it is usually stored twice. A well-formed marketing or product email carries both an HTML version and a plain-text version, wrapped in MIME parts and separated by a boundary marker. The viewer above shows each version on its own tab. Bodies are commonly encoded as quoted-printable or base64 so that non-ASCII characters survive transport, which is why the raw text can look scrambled until a viewer decodes it.
Attachments are stored inline as more MIME parts, base64-encoded, each with its own filename and content type. The viewer lists them by name, type, and size, and lets you save any one back out.
This is the message as it sits on disk. How it moves between servers is the transport layer, covered in SMTP ports and email protocols. The same headers you inspect in a saved file are what Loops writes when it sends transactional and marketing email from one contact record.
Is opening an .eml file private?
The file itself never leaves your browser. FileReader reads it locally, and the viewer does not send its contents to Loops or another server. Clear the message or close the tab to remove it from the page.
The HTML preview runs in a sandbox with scripts, forms, and remote content blocked. Embedded images such as data URLs can render, but tracking pixels, external stylesheets, frames, and other network resources do not load.
FAQ
Can I open an .eml file without Outlook?
Yes. An .eml file is a standard text-based message, so any tool that reads the format works. Use the viewer on this page, open the file in Apple Mail or another client, or open the raw source in any text editor.
Why does the body of my .eml file look like random characters?
Email bodies are usually encoded for transport, most often as quoted-printable or base64, so that formatting and non-ASCII characters survive. The characters are the encoded form. A viewer decodes them back into readable text and rendered HTML.
What is the difference between .eml and .msg?
.eml is the open, standards-based format defined by RFC 5322 and MIME, readable by almost any mail tool. .msg is Outlook's proprietary format and generally needs Outlook or a converter to open. This tool reads .eml.
Can I check my subject line before I send?
That is a different job. Once you know what a message looks like on disk, the subject line tester shows how your subject and preview text will appear across inboxes.
What's next
Related reading and free tools.