What is a .eml file?
Email Message · Data · Internet Engineering Task Force · 1982
EML stores a single email message as a plain-text file, headers and body together, in essentially the same format mail servers use to pass messages around. Dragging a message out of Thunderbird, Apple Mail or many webmail clients onto your desktop creates one.
What is a .eml file used for?
An EML file is a single saved email: the message headers (From, To, Subject, Date and the rest) followed by the body, in the same plain-text format email servers actually exchange internally.
Attachments travel inside the same file, encoded as MIME parts, so an EML with photos attached is larger than the visible text alone; that encoding is what lets a plain-text file carry images and other binaries.
Thunderbird, Apple Mail and most webmail 'save message' or 'download' features produce an EML, which is why dragging an email out of one of those apps onto your desktop usually creates a .eml file.
The header-and-body structure follows RFC 5322 (the modern successor to RFC 822), the same specification that defines how mail servers format a message in the first place.
What opens a .eml file?
The .eml format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- Outlook
- Thunderbird
- any text editor (headers)
macOS
- Thunderbird
Linux
- Thunderbird
- any text editor
Web
- Some webmail 'import' features
Open a .eml file step by step
- Confirm the file really is a .eml. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with Outlook or Thunderbird.
- On Mac, use Mail or Thunderbird.
- On Linux, try Thunderbird or any text editor.
- Still stuck? Convert the .eml to PDF, which opens more widely.
Why can't I open my .eml file?
Almost always because no installed app understands EML. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .eml at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
How to convert a .eml file
You can convert a .eml file to PDF using a conversion tool or the export menu of an app that opens it.
EML has no fixed magic number, so there is no signature table on this page. Its bytes alone do not prove the format: identification relies on the extension, the structure of the content and the program that created it. The magic-numbers reference lists the formats that do carry one.
Frequently asked questions
What is a .eml file?
EML stores a single email message as a plain-text file, headers and body together, in essentially the same format mail servers use to pass messages around. Dragging a message out of Thunderbird, Apple Mail or many webmail clients onto your desktop creates one.
How do I open an EML file?
Double-click it and it opens in your default mail app, such as Outlook, Thunderbird or Apple Mail. Since it is plain text underneath, a text editor also shows the raw headers and body.
What is the difference between EML and MSG?
Both save a single email to a file. EML is the plain-text format used across most mail clients (Thunderbird, Apple Mail, and Gmail exports), while MSG is Outlook's own binary format. Outlook can usually open an EML, and most mail apps can convert an MSG dragged in from Outlook.
Related formats
Sources
Details on this page were checked against authoritative references. How sources are ranked and what is deliberately left out is set out in the methodology.