.eml (RFC 822) file format

.eml · individual email file · introduced 1982 by IETF

What is a .eml (RFC 822) file?

An .eml file is one email message saved on its own using the RFC 822 / RFC 5322 format every email server speaks. They are mostly plain text — headers, then a body, then optional MIME attachments. Every modern email client opens .eml files, and tools like ripmime can split out the attachments.

Most readers reach this page after double-clicking a .eml file and finding their operating system unsure what to do with it. The good news: .eml (RFC 822) is a well-understood format with mature tooling on every major platform. It is supported in one click by mainstream archivers on Windows, macOS, and Linux.

How to extract a .eml (RFC 822) file

Opening a .eml file is straightforward on every modern operating system. The exact steps depend on which platform you are on:

On Windows

Locate the .eml file in File Explorer.
Right-click the file. If you have 7-Zip installed, choose 7-Zip → Extract Here. On Windows 11 the built-in extractor handles ZIP, 7z, RAR and several other formats directly through Extract All…
If prompted, pick a destination folder and click Extract.
The extracted files appear in a folder next to the original archive.

On macOS

Find the .eml file in Finder.
Install The Unarchiver from the Mac App Store, or Keka for both creating and extracting.
Right-click the file → Open With → The Unarchiver (or just double-click after Unarchiver is set as the default).
The extracted folder appears next to the archive.

On Linux

Use your file manager: right-click the archive → Extract Here (file-roller on GNOME, Ark on KDE).

On the command line, run one of:

7z x archive.eml    # works for almost any format

The files appear in the current directory.

How to create a .eml (RFC 822) file

To pack files into a .eml archive, you typically need an archiver that supports writing this format. Not every tool can create every format — for example, only WinRAR can create real RAR files. The sidebar lists the software known to read and write .eml (RFC 822).

On the command line, the canonical create command is:

# Use 7-Zip, PeaZip, or the format's reference tool to create .eml files.

If you regularly create archives at scale, a dedicated archive automation suite can wrap this command in scheduled jobs, integrity checks, and offsite replication.

Strengths

Universal format
Plain text
Trivial to parse

Weaknesses and limitations

One file per message — large mailboxes are unwieldy

Typical use cases

Single email archives
Forwarding raw email
Forensic analysis

Technical details

.eml (RFC 822) uses the MIME algorithm and is identified on disk by the magic byte sequence (plain text headers). The standard MIME type is message/rfc822. The format is an open specification and is free for any use.

Frequently asked questions

Is .eml (RFC 822) safe to open?

Archive files are containers — they are only as safe as what they contain. A .eml from a trusted source is fine; one received from a stranger can hold malicious executables, scripts, or files engineered to exploit bugs in your archiver. Always keep your archiver updated, and never run unknown executables that come out of an archive. A safe workflow is to extract into a sandbox and scan the contents before opening anything.

What is the maximum file size?

Modern implementations support archives in the multi-terabyte range. The practical limit is your filesystem (FAT32 caps at 4 GB; ext4, NTFS, APFS, and exFAT all comfortably handle multi-TB files).

Can I password-protect a .eml (RFC 822)?

Some archivers can wrap .eml (RFC 822) files in an encrypted container, but the format itself does not always include built-in encryption. Check your archiver's documentation.

How does .eml (RFC 822) compare to other formats?

See our format comparison pages such as ZIP vs 7z, ZIP vs RAR, and tar.gz vs tar.xz for side-by-side feature tables.