The short answer
- EML is an email file format that usually stores one message using the Internet Message Format, but copying the file alone may not include every attachment.
- On Windows, drag the EML file into the reading pane in new Outlook, or use Open with; double-clicking also works after association. Outlook on the web supports dragging EML into the reading pane. On a Mac, Apple Mail is a compatible client. Thunderbird is another compatible email client. A text editor can show the raw message, although encoded bodies and attachments may not be readable as ordinary text.
- Assess the sender and contents before opening attachments. MIME can carry application data with active behavior, so risk depends on the content and how the viewer handles it. Raw text is not automatically harmless: RFC 5322 warns that terminals may interpret control characters and escape sequences. Use a viewer that handles these sequences appropriately.
EML email files: opening, attachments and conversion
An EML file usually contains a message in RFC 5322 format. Header fields use a name, colon and value; a blank line separates the headers from the optional body, and standard line endings are CRLF. MIME supports different character sets, non-text content and multipart bodies. The Library of Congress notes that no separate specification is known to define EML storage as a filesystem format.
Converting an EML body to plain text may lose information. MIME multipart/alternative can contain different representations of the same content, and a client chooses one it can display. Preserve the original EML and check the resulting text and attachments separately; an externally referenced attachment may not be in the EML.
How to open it
On Windows, drag the EML file into the reading pane in new Outlook, or use Open with; double-clicking also works after association. Outlook on the web supports dragging EML into the reading pane. On a Mac, Apple Mail is a compatible client. Thunderbird is another compatible email client. A text editor can show the raw message, although encoded bodies and attachments may not be readable as ordinary text.
On Windows, drag the EML file into the reading pane in new Outlook, or use Open with; double-clicking also works after association. Outlook on the web supports dragging EML into the reading pane. On a Mac, Apple Mail is a compatible client. Thunderbird is another compatible email client. A text editor can show the raw message, although encoded bodies and attachments may not be readable as ordinary text.
Converting an EML body to plain text may lose information. MIME multipart/alternative can contain different representations of the same content, and a client chooses one it can display. Preserve the original EML and check the resulting text and attachments separately; an externally referenced attachment may not be in the EML.
File safety
Assess the sender and contents before opening attachments. MIME can carry application data with active behavior, so risk depends on the content and how the viewer handles it. Raw text is not automatically harmless: RFC 5322 warns that terminals may interpret control characters and escape sequences. Use a viewer that handles these sequences appropriately.
An unknown sender, a name ending in two extensions, or contents that do not match the extension — check before you open it.
Converting it
Converting an EML body to plain text may lose information. MIME multipart/alternative can contain different representations of the same content, and a client chooses one it can display. Preserve the original EML and check the resulting text and attachments separately; an externally referenced attachment may not be in the EML.
Convert a copy, never the original, then compare quality, metadata, and layout against what you started with.
Common questions
What is an EML file used for?
EML usually saves one email as a file, including its headers and optional body. MIME content may also include attachments, but some attachments can be stored externally.
How do I open an EML email file?
Use a compatible email client such as Outlook, Thunderbird or Apple Mail. A text editor can display the raw content, but does not necessarily decode it into a readable email.
How do I open EML in new Outlook on Windows?
Drag the file into the reading pane in new Outlook. You can also right-click and choose Open with, or double-click after associating EML files with the application.
How do I open an EML file on a Mac with Apple Mail?
Use Apple Mail as the application for opening the EML file. The Library of Congress lists Apple Mail as a compatible client; a text editor can alternatively show the raw message.
How do I open an EML file in Outlook on the web?
Drag the EML file into the Outlook on the web reading pane. Microsoft documents this opening method; it does not establish that the file stays entirely on your device.
Why does the text in an EML email look garbled?
The raw file may show an encoded MIME body instead of decoded text. Try a compatible email client. MIME supports non-ASCII character sets; if the text still looks wrong, inspect the message's character-set information.
How do I extract attachments from an EML file, and why are some missing?
Open the message in a compatible client and use its attachment-saving controls for attachments it displays. If one is missing, it may be externally referenced rather than embedded; obtain the accompanying external file.
Should I keep EML or plain text to preserve an email?
Keep EML when you need the original message structure and its MIME content. Plain text is useful for reading text, but conversion may lose information and does not preserve the full email package.
Can converting EML to plain text lose information?
Yes. RFC 2046 explicitly identifies conversion to plain text as a mapping that may lose information. Preserve the EML and check the converted body and any attachments separately.
Is an unfamiliar EML file safe to open?
The extension alone cannot establish safety. MIME content may carry active application data, and viewers handle it differently. Assess the source and attachments; raw viewing in a terminal also has control-sequence risks.
Does a correctly displayed EML file prove that its contents are trustworthy?
No. Successful display shows that the viewer can interpret the message. It does not establish the truth of its claims or the safety of its attachments.
Related formats
Sources
Email (Electronic Mail Format) · 美国国会图书馆
RFC 5322: Internet Message Format · IETF / RFC Editor
RFC 2046: Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types · IETF / RFC Editor
Open .eml, .msg, and .oft files in new Outlook and Outlook on the web · Microsoft 官方支持