What Is an EML File? How to Open & Read One

A .eml file is one email message saved as a plain-text file in the internet's standard message format (RFC 822, today RFC 5322). It contains everything the email is made of — the headers, the body in every version the sender included, and the attachments — in a single portable file that opens in virtually any mail client.

If a .eml just landed on your desktop and won't open, skip to how to open one. If you're deciding what to keep email in for the long run, the short version is: .eml is the format to use, and here's why.

What's inside a .eml file?

Open one in a text editor and you'll see the email as mail servers actually see it:

From: Acme Billing <[email protected]>
To: [email protected]
Subject: Invoice #4471 - June services
Date: Fri, 3 Jul 2026 09:12:44 +0000
Message-ID: <[email protected]>
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="boundary-42"

--boundary-42
Content-Type: text/plain; charset=UTF-8

Hi - your June invoice is attached.
--boundary-42
Content-Type: application/pdf; name="invoice-4471.pdf"
Content-Transfer-Encoding: base64

JVBERi0xLjQKJcOkw7zDtsOfCjIgMCBvYmoK...

Three things worth noticing:

• The headers are evidence. Message-ID, Date, Received chains, and authentication results (SPF/DKIM) travel with the file. A rendered PDF "print" of an email loses all of this; a .eml keeps it. (Curious what yours say? Paste them into our email header analyzer.)
• Attachments are embedded. They're encoded (usually base64) inside the file, so one .eml is genuinely one complete email.
• It's plain text. No database, no proprietary container. If every mail client on earth disappeared, the message would still be readable.

How to open a .eml file

A .eml opens three ways, on any system:

1. Open it online — drag the file into our free EML viewer. It parses the message in your browser, so nothing is uploaded anywhere. This is the fastest route when you don't want to install a thing.
2. Open it in a mail client — double-click it. Outlook, Apple Mail, Thunderbird, and Evolution all read .eml natively, because it's what mail programs speak.
3. Open it in a text editor — right-click → Open with → any editor. You'll see the raw headers and body. This is always safe: a text editor renders nothing and runs nothing.

By device

Opening a .eml in Gmail, Outlook, or without any client

• Without Outlook (or any mail app): use the browser EML viewer or a text editor. Neither needs a mail program installed — this is the simplest answer if you don't have Outlook and don't want it.
• In Outlook: double-clicking usually works. If Windows has associated .eml with something else, right-click the file → Open with → Outlook.
• In Gmail: Gmail's web app has no built-in .eml opener. The reliable routes are the browser viewer above, or dragging the file into a desktop client (Thunderbird or Apple Mail) that's synced to your Gmail over IMAP — which also files the message back into your account.

.eml vs .msg vs MBOX

These three formats come up together constantly:

If you're choosing a format to keep email in for years, .eml wins on every axis that matters: it's standard, it's per-message (so you can find, share, or delete one email without touching the rest), and it needs no special software. .msg locks you to Outlook; MBOX locks each message inside a mailbox blob you can't browse without importing it first.

Why .eml is the right format for email backup

A backup format should still work decades from now, without the company or app that created it. That's the case for .eml in a way it isn't for anything else:

• Fidelity. The file is the original message — not an export, a rendering, or a database row. Headers and attachments included, byte for byte.
• No lock-in. Standard format, readable by any client or any programming language's email library.
• One file per email. Storage services, search tools, and file managers all handle it naturally.

This is why InboxBucket archives every email as a .eml file in your own Google Drive, OneDrive, Dropbox, or S3 — files you can open in twenty years, in whatever replaces today's mail clients. If you're weighing backup approaches more broadly, see our comparison of email backup methods; for the Gmail-specific setup, see how to back up Gmail to Google Drive.

FAQ

Is a .eml file safe to open?

Opening the file in a text editor or a browser viewer is always safe — nothing is executed. Opening it in a mail client renders the message, so the usual email caution applies to links and attachments inside it: a .eml can carry the same phishing or malware an email can, because it is an email. If you're unsure of the source, view the raw source in a text editor rather than letting a client render it.

Can I open a .eml file on my phone?

Yes. Neither iPhone nor Android opens .eml natively, but a browser EML viewer works on both — open the file in your mobile browser and it renders in the page. On Android you can also open .eml in the Outlook or Thunderbird apps.

How do I open a .eml file without Outlook?

Use a browser-based EML viewer or any text editor — neither needs Outlook or any mail program installed. Thunderbird (free, on every OS) is the option if you'd rather have a full mail client render it.

Can I convert .eml to PDF?

Yes — use our free EML to PDF converter (runs in your browser, nothing is uploaded), or open the file in any mail client and print to PDF. Keep the original .eml alongside it, though: the PDF is a picture of the message, while the .eml preserves the headers and attachments that make it verifiable.

How do I save an email as a .eml file?

Most desktop clients support it directly: drag a message out of Apple Mail or Thunderbird, or use File → Save As in Outlook (choose the .eml or "message" type where offered). Webmail like Gmail offers "Download message" (⋮ menu) which saves .eml. An archiving service can do this automatically for every incoming mail.