.eml

What is a .eml file?

EML is the standard email file format — a single message in MIME format that most email clients can open.

Use caution
Type Document
By IETF (RFC 5322)
MIME message/rfc822

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What is it

EML is email in its most portable form. Based on the RFC 5322 standard, an EML file contains the complete email message — headers, body (plain text and HTML), embedded images, and attachments — in MIME format. Unlike MSG (Outlook-proprietary), EML is an open standard that virtually every email client understands.

The format is plain text at its core. You can open an EML file in any text editor and read the raw email headers and body content. The MIME structure separates the message into parts: text, HTML, attachments encoded in base64. Email clients parse this structure to render the formatted message.

Thunderbird, Apple Mail, Windows Mail, and most email clients open EML files with a double-click. Drag an EML file into Gmail's compose window to forward it. For bulk email archival, EML is the preferred format because it's standard, readable, and well-supported by archiving tools.

Technical details
Full Name
Email Message File
MIME Type
message/rfc822
Developer
IETF (RFC 5322)
Magic Bytes
N/A
Safety
.eml requires caution. Email files can contain phishing links and malicious attachments. Exercise caution with EML from unknown sources.
What opens it
Thunderbird
FREE Windows / Mac / Linux
Apple Mail
FREE Mac
Windows Mail
FREE Windows
FAQ
How do I open an EML file?
Double-click it — most email clients (Thunderbird, Apple Mail, Windows Mail) open EML natively. You can also open it in a text editor to see the raw email content.
What's the difference between EML and MSG?
EML is the open standard (MIME/RFC 5322) supported by all email clients. MSG is Microsoft's proprietary format specific to Outlook. EML is more portable; MSG preserves Outlook-specific features.
Related formats